[#1848] pgsql_cb_dhcp6_unittest.cc added

1 files changed, 4856 insertions, 0 deletions

diff --git a/src/hooks/dhcp/pgsql_cb/tests/pgsql_cb_dhcp6_unittest.cc b/src/hooks/dhcp/pgsql_cb/tests/pgsql_cb_dhcp6_unittest.cc
new file mode 100644
index 0000000000..92fdd34edc
--- /dev/null
+++ b/src/hooks/dhcp/pgsql_cb/tests/pgsql_cb_dhcp6_unittest.cc
@@ -0,0 +1,4856 @@
+// Copyright (C) 2021 Internet Systems Consortium, Inc. ("ISC")
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#include <config.h>
+#include <pgsql_cb_dhcp6.h>
+#include <asiolink/addr_utilities.h>
+#include <database/database_connection.h>
+#include <database/db_exceptions.h>
+#include <database/testutils/schema.h>
+#include <dhcp/dhcp6.h>
+#include <dhcp/libdhcp++.h>
+#include <dhcp/option6_addrlst.h>
+#include <dhcp/option_int.h>
+#include <dhcp/option_space.h>
+#include <dhcp/option_string.h>
+#include <dhcpsrv/cfgmgr.h>
+#include <dhcpsrv/config_backend_dhcp6_mgr.h>
+#include <dhcpsrv/pool.h>
+#include <dhcpsrv/subnet.h>
+#include <dhcpsrv/testutils/pgsql_generic_backend_unittest.h>
+#include <dhcpsrv/testutils/test_utils.h>
+#include <pgsql/testutils/pgsql_schema.h>
+#include <testutils/multi_threading_utils.h>
+
+#include <boost/shared_ptr.hpp>
+#include <gtest/gtest.h>
+#include <map>
+#include <sstream>
+
+using namespace isc;
+using namespace isc::asiolink;
+using namespace isc::db;
+using namespace isc::db::test;
+using namespace isc::data;
+using namespace isc::dhcp;
+using namespace isc::dhcp::test;
+using namespace isc::process;
+using namespace isc::test;
+namespace ph = std::placeholders;
+
+namespace {
+
+/// @brief Test implementation of the Postgres configuration backend.
+///
+/// It exposes protected members of the @c PgSqlConfigBackendDHCPv6.
+class TestPgSqlConfigBackendDHCPv6 : public PgSqlConfigBackendDHCPv6 {
+public:
+
+    /// @brief Constructor.
+    ///
+    /// @param parameters A data structure relating keywords and values
+    /// concerned with the database.
+    explicit TestPgSqlConfigBackendDHCPv6(const DatabaseConnection::ParameterMap& parameters)
+        : PgSqlConfigBackendDHCPv6(parameters) {
+    }
+
+    using PgSqlConfigBackendDHCPv6::base_impl_;
+
+};
+
+/// @brief Test fixture class for @c PgSqlConfigBackendDHCPv6.
+///
+/// @todo The tests we're providing here only test cases when the
+/// server selector is set to 'ALL' (configuration elements belong to
+/// all servers). Currently we have no API to insert servers into
+/// the database, and therefore we can't test the case when
+/// configuration elements are assigned to particular servers by
+/// server tags. We will have to expand existing tests when
+/// the API is extended allowing for inserting servers to the
+/// database.
+class PgSqlConfigBackendDHCPv6Test : public PgSqlGenericBackendTest {
+public:
+
+    /// @brief Constructor.
+    PgSqlConfigBackendDHCPv6Test()
+        : test_subnets_(), test_networks_(), test_option_defs_(),
+          test_options_(), test_servers_(), timestamps_(), cbptr_(),
+          audit_entries_() {
+        // Ensure we have the proper schema with no transient data.
+        createPgSQLSchema();
+
+        try {
+            // Create Postgres connection and use it to start the backend.
+            DatabaseConnection::ParameterMap params =
+                DatabaseConnection::parse(validPgSQLConnectionString());
+            cbptr_.reset(new TestPgSqlConfigBackendDHCPv6(params));
+
+        } catch (...) {
+            std::cerr << "*** ERROR: unable to open database. The test\n"
+                         "*** environment is broken and must be fixed before\n"
+                         "*** the Postgres tests will run correctly.\n"
+                         "*** The reason for the problem is described in the\n"
+                         "*** accompanying exception output.\n";
+            throw;
+        }
+
+        // Create test data.
+        initTestServers();
+        initTestOptions();
+        initTestSubnets();
+        initTestSharedNetworks();
+        initTestOptionDefs();
+        initTimestamps();
+    }
+
+    /// @brief Destructor.
+    virtual ~PgSqlConfigBackendDHCPv6Test() {
+        cbptr_.reset();
+        // If data wipe enabled, delete transient data otherwise destroy the schema.
+        destroyPgSQLSchema();
+    }
+
+    /// @brief Counts rows in a selected table in Postgres database.
+    ///
+    /// This method can be used to verify that some configuration elements were
+    /// deleted from a selected table as a result of cascade delete or a trigger.
+    /// For example, deleting a subnet should trigger deletion of its address
+    /// pools and options. By counting the rows on each table we can determine
+    /// whether the deletion took place on all tables for which it was expected.
+    ///
+    /// @param table Table name.
+    /// @return Number of rows in the specified table.
+    size_t countRows(const std::string& table) const {
+        auto p = boost::dynamic_pointer_cast<TestPgSqlConfigBackendDHCPv6>(cbptr_);
+        if (!p) {
+            ADD_FAILURE() << "cbptr_ does not cast to TestPgSqlConfigBackendDHCPv6";
+            return (0);
+        }
+
+        // Reuse the existing connection of the backend.
+        auto impl = boost::dynamic_pointer_cast<PgSqlConfigBackendImpl>(p->base_impl_);
+        auto& conn = impl->conn_;
+
+        return (PgSqlGenericBackendTest::countRows(conn, table));
+    }
+
+    /// @brief Creates several servers used in tests.
+    void initTestServers() {
+        test_servers_.push_back(Server::create(ServerTag("server1"), "this is server 1"));
+        test_servers_.push_back(Server::create(ServerTag("server1"), "this is server 1 bis"));
+        test_servers_.push_back(Server::create(ServerTag("server2"), "this is server 2"));
+        test_servers_.push_back(Server::create(ServerTag("server3"), "this is server 3"));
+    }
+
+    /// @brief Creates several subnets used in tests.
+    void initTestSubnets() {
+        // First subnet includes all parameters.
+        std::string interface_id_text = "whale";
+        OptionBuffer interface_id(interface_id_text.begin(), interface_id_text.end());
+        OptionPtr opt_interface_id(new Option(Option::V6, D6O_INTERFACE_ID,
+                                              interface_id));
+        ElementPtr user_context = Element::createMap();
+        user_context->set("foo", Element::create("bar"));
+
+        Subnet6Ptr subnet(new Subnet6(IOAddress("2001:db8::"),
+                                      64, 30, 40, 50, 60, 1024));
+        subnet->allowClientClass("home");
+        subnet->setIface("eth1");
+        subnet->setInterfaceId(opt_interface_id);
+        subnet->setT2(323212);
+        subnet->addRelayAddress(IOAddress("2001:db8:1::2"));
+        subnet->addRelayAddress(IOAddress("2001:db8:3::4"));
+        subnet->setT1(1234);
+        subnet->requireClientClass("required-class1");
+        subnet->requireClientClass("required-class2");
+        subnet->setReservationsGlobal(false);
+        subnet->setReservationsInSubnet(false);
+        subnet->setContext(user_context);
+        subnet->setValid(555555);
+        subnet->setPreferred(4444444);
+        subnet->setCalculateTeeTimes(true);
+        subnet->setT1Percent(0.345);
+        subnet->setT2Percent(0.444);
+        subnet->setDdnsSendUpdates(false);
+
+        Pool6Ptr pool1(new Pool6(Lease::TYPE_NA,
+                                 IOAddress("2001:db8::10"),
+                                 IOAddress("2001:db8::20")));
+        subnet->addPool(pool1);
+
+        Pool6Ptr pool2(new Pool6(Lease::TYPE_NA,
+                                 IOAddress("2001:db8::50"),
+                                 IOAddress("2001:db8::60")));
+        subnet->addPool(pool2);
+
+        Pool6Ptr pdpool1(new Pool6(Lease::TYPE_PD,
+                                   IOAddress("2001:db8:a::"), 48, 64));
+        subnet->addPool(pdpool1);
+
+        Pool6Ptr pdpool2(new Pool6(Lease::TYPE_PD,
+                                   IOAddress("2001:db8:b::"), 48, 64));
+        subnet->addPool(pdpool2);
+
+        // Add several options to the subnet.
+        subnet->getCfgOption()->add(test_options_[0]->option_,
+                                    test_options_[0]->persistent_,
+                                    test_options_[0]->space_name_);
+
+        subnet->getCfgOption()->add(test_options_[1]->option_,
+                                    test_options_[1]->persistent_,
+                                    test_options_[1]->space_name_);
+
+        subnet->getCfgOption()->add(test_options_[2]->option_,
+                                    test_options_[2]->persistent_,
+                                    test_options_[2]->space_name_);
+
+        test_subnets_.push_back(subnet);
+
+        // Adding another subnet with the same subnet id to test
+        // cases that this second instance can override existing
+        // subnet instance.
+        subnet.reset(new Subnet6(IOAddress("2001:db8:1::"),
+                                 48, 20, 30, 40, 50, 1024));
+
+        pool1.reset(new Pool6(Lease::TYPE_NA,
+                              IOAddress("2001:db8:1::10"),
+                              IOAddress("2001:db8:1::20")));
+        subnet->addPool(pool1);
+
+        pool1->getCfgOption()->add(test_options_[3]->option_,
+                                   test_options_[3]->persistent_,
+                                   test_options_[3]->space_name_);
+
+        pool1->getCfgOption()->add(test_options_[4]->option_,
+                                   test_options_[4]->persistent_,
+                                   test_options_[4]->space_name_);
+
+        pool2.reset(new Pool6(Lease::TYPE_NA,
+                              IOAddress("2001:db8:1::50"),
+                              IOAddress("2001:db8:1::60")));
+        subnet->addPool(pool2);
+
+        pool2->allowClientClass("work");
+        pool2->requireClientClass("required-class3");
+        pool2->requireClientClass("required-class4");
+        user_context = Element::createMap();
+        user_context->set("bar", Element::create("foo"));
+        pool2->setContext(user_context);
+
+        pdpool1.reset(new Pool6(IOAddress("2001:db8:c::"), 48, 64,
+                                IOAddress("2001:db8:c::1"), 96));
+        subnet->addPool(pdpool1);
+
+        pdpool1->getCfgOption()->add(test_options_[3]->option_,
+                                     test_options_[3]->persistent_,
+                                     test_options_[3]->space_name_);
+
+        pdpool1->getCfgOption()->add(test_options_[4]->option_,
+                                     test_options_[4]->persistent_,
+                                     test_options_[4]->space_name_);
+
+        // Create the prefix delegation pool with an excluded prefix.
+        pdpool2.reset(new Pool6(IOAddress("2001:db8:d::"), 48, 64,
+                                IOAddress("2001:db8:d::2000"), 120));
+
+        subnet->addPool(pdpool2);
+
+        pdpool2->allowClientClass("work");
+        pdpool2->requireClientClass("required-class3");
+        pdpool2->requireClientClass("required-class4");
+        user_context = Element::createMap();
+        user_context->set("bar", Element::create("foo"));
+        pdpool2->setContext(user_context);
+
+        test_subnets_.push_back(subnet);
+
+        subnet.reset(new Subnet6(IOAddress("2001:db8:3::"),
+                                 64, 20, 30, 40, 50, 2048));
+        Triplet<uint32_t> null_timer;
+        subnet->setPreferred(null_timer);
+        subnet->setT1(null_timer);
+        subnet->setT2(null_timer);
+        subnet->setValid(null_timer);
+        subnet->setPreferred(null_timer);
+        subnet->setDdnsSendUpdates(true);
+        subnet->setDdnsOverrideNoUpdate(true);
+        subnet->setDdnsOverrideClientUpdate(false);
+        subnet->setDdnsReplaceClientNameMode(D2ClientConfig::ReplaceClientNameMode::RCM_WHEN_PRESENT);
+        subnet->setDdnsGeneratedPrefix("myhost");
+        subnet->setDdnsQualifyingSuffix("example.org");
+
+        subnet->getCfgOption()->add(test_options_[0]->option_,
+                                    test_options_[0]->persistent_,
+                                    test_options_[0]->space_name_);
+
+        test_subnets_.push_back(subnet);
+
+        // Add a subnet with all defaults.
+        subnet.reset(new Subnet6(IOAddress("2001:db8:4::"), 64,
+                                 Triplet<uint32_t>(), Triplet<uint32_t>(),
+                                 Triplet<uint32_t>(), Triplet<uint32_t>(),
+                                 4096));
+        test_subnets_.push_back(subnet);
+    }
+
+    /// @brief Creates several subnets used in tests.
+    void initTestSharedNetworks() {
+        ElementPtr user_context = Element::createMap();
+        user_context->set("foo", Element::create("bar"));
+
+        std::string interface_id_text = "fish";
+        OptionBuffer interface_id(interface_id_text.begin(),
+                                  interface_id_text.end());
+        OptionPtr opt_interface_id(new Option(Option::V6, D6O_INTERFACE_ID,
+                                              interface_id));
+
+        SharedNetwork6Ptr shared_network(new SharedNetwork6("level1"));
+        shared_network->allowClientClass("foo");
+        shared_network->setIface("eth1");
+        shared_network->setInterfaceId(opt_interface_id);
+        shared_network->setT2(323212);
+        shared_network->addRelayAddress(IOAddress("2001:db8:1::2"));
+        shared_network->addRelayAddress(IOAddress("2001:db8:3::4"));
+        shared_network->setT1(1234);
+        shared_network->requireClientClass("required-class1");
+        shared_network->requireClientClass("required-class2");
+        shared_network->setReservationsGlobal(false);
+        shared_network->setReservationsInSubnet(false);
+        shared_network->setContext(user_context);
+        shared_network->setValid(5555);
+        shared_network->setPreferred(4444);
+        shared_network->setCalculateTeeTimes(true);
+        shared_network->setT1Percent(0.345);
+        shared_network->setT2Percent(0.444);
+        shared_network->setDdnsSendUpdates(false);
+
+        // Add several options to the shared network.
+        shared_network->getCfgOption()->add(test_options_[2]->option_,
+                                            test_options_[2]->persistent_,
+                                            test_options_[2]->space_name_);
+
+        shared_network->getCfgOption()->add(test_options_[3]->option_,
+                                            test_options_[3]->persistent_,
+                                            test_options_[3]->space_name_);
+
+        shared_network->getCfgOption()->add(test_options_[4]->option_,
+                                            test_options_[4]->persistent_,
+                                            test_options_[4]->space_name_);
+
+        test_networks_.push_back(shared_network);
+
+        // Adding another shared network called "level1" to test
+        // cases that this second instance can override existing
+        // "level1" instance.
+        shared_network.reset(new SharedNetwork6("level1"));
+        test_networks_.push_back(shared_network);
+
+        // Add more shared networks.
+        shared_network.reset(new SharedNetwork6("level2"));
+        Triplet<uint32_t> null_timer;
+        shared_network->setPreferred(null_timer);
+        shared_network->setT1(null_timer);
+        shared_network->setT2(null_timer);
+        shared_network->setValid(null_timer);
+        shared_network->setPreferred(null_timer);
+        shared_network->setDdnsSendUpdates(true);
+        shared_network->setDdnsOverrideNoUpdate(true);
+        shared_network->setDdnsOverrideClientUpdate(false);
+        shared_network->setDdnsReplaceClientNameMode(D2ClientConfig::ReplaceClientNameMode::RCM_WHEN_PRESENT);
+        shared_network->setDdnsGeneratedPrefix("myhost");
+        shared_network->setDdnsQualifyingSuffix("example.org");
+
+        shared_network->getCfgOption()->add(test_options_[0]->option_,
+                                            test_options_[0]->persistent_,
+                                            test_options_[0]->space_name_);
+        test_networks_.push_back(shared_network);
+
+        shared_network.reset(new SharedNetwork6("level3"));
+        test_networks_.push_back(shared_network);
+    }
+
+    /// @brief Creates several option definitions used in tests.
+    void initTestOptionDefs() {
+        ElementPtr user_context = Element::createMap();
+        user_context->set("foo", Element::create("bar"));
+
+        OptionDefinitionPtr option_def(new OptionDefinition("foo", 1234,
+                                                            DHCP6_OPTION_SPACE,
+                                                            "string",
+                                                            "espace"));
+        test_option_defs_.push_back(option_def);
+
+        option_def.reset(new OptionDefinition("bar", 1234, DHCP6_OPTION_SPACE,
+                                              "uint32", true));
+        test_option_defs_.push_back(option_def);
+
+        option_def.reset(new OptionDefinition("fish", 5235, DHCP6_OPTION_SPACE,
+                                              "record", true));
+        option_def->addRecordField("uint32");
+        option_def->addRecordField("string");
+        test_option_defs_.push_back(option_def);
+
+        option_def.reset(new OptionDefinition("whale", 20236, "xyz", "string"));
+        test_option_defs_.push_back(option_def);
+
+        option_def.reset(new OptionDefinition("bar", 1234, DHCP6_OPTION_SPACE,
+                                              "uint64", true));
+        test_option_defs_.push_back(option_def);
+    }
+
+    /// @brief Creates several DHCP options used in tests.
+    void initTestOptions() {
+        ElementPtr user_context = Element::createMap();
+        user_context->set("foo", Element::create("bar"));
+
+        OptionDefSpaceContainer defs;
+
+        OptionDescriptor desc =
+            createOption<OptionString>(Option::V6, D6O_NEW_POSIX_TIMEZONE,
+                                       true, false, "my-timezone");
+        desc.space_name_ = DHCP6_OPTION_SPACE;
+        desc.setContext(user_context);
+        test_options_.push_back(OptionDescriptorPtr(new OptionDescriptor(desc)));
+
+        desc = createOption<OptionUint8>(Option::V6, D6O_PREFERENCE,
+                                         false, true, 64);
+        desc.space_name_ = DHCP6_OPTION_SPACE;
+        test_options_.push_back(OptionDescriptorPtr(new OptionDescriptor(desc)));
+
+        desc = createOption<OptionUint32>(Option::V6, 1, false, false, 312131),
+        desc.space_name_ = "vendor-encapsulated-options";
+        test_options_.push_back(OptionDescriptorPtr(new OptionDescriptor(desc)));
+
+        desc = createAddressOption<Option6AddrLst>(1254, true, true,
+                                                   "2001:db8::3");
+        desc.space_name_ = DHCP6_OPTION_SPACE;
+        test_options_.push_back(OptionDescriptorPtr(new OptionDescriptor(desc)));
+
+        desc = createEmptyOption(Option::V6, 1, true);
+        desc.space_name_ = "isc";
+        test_options_.push_back(OptionDescriptorPtr(new OptionDescriptor(desc)));
+
+        desc = createAddressOption<Option6AddrLst>(2, false, true,
+                                                   "2001:db8:1::5",
+                                                   "2001:db8:1::3",
+                                                   "2001:db8:3::4");
+        desc.space_name_ = "isc";
+        test_options_.push_back(OptionDescriptorPtr(new OptionDescriptor(desc)));
+
+        desc = createOption<OptionString>(Option::V6, D6O_NEW_POSIX_TIMEZONE,
+                                          true, false, "my-timezone-2");
+        desc.space_name_ = DHCP6_OPTION_SPACE;
+        desc.setContext(user_context);
+        test_options_.push_back(OptionDescriptorPtr(new OptionDescriptor(desc)));
+
+        desc = createOption<OptionString>(Option::V6, D6O_NEW_POSIX_TIMEZONE,
+                                          true, false, "my-timezone-3");
+        desc.space_name_ = DHCP6_OPTION_SPACE;
+        desc.setContext(user_context);
+        test_options_.push_back(OptionDescriptorPtr(new OptionDescriptor(desc)));
+
+        // Add definitions for DHCPv6 non-standard options in case we need to
+        // compare subnets, networks and pools in JSON format. In that case,
+        // the @c toElement functions require option definitions to generate the
+        // proper output.
+        defs.addItem(OptionDefinitionPtr(new OptionDefinition(
+                         "vendor-encapsulated-1", 1,
+                         "vendor-encapsulated-options", "uint32")));
+        defs.addItem(OptionDefinitionPtr(new OptionDefinition(
+                         "option-1254", 1254, DHCP6_OPTION_SPACE,
+                         "ipv6-address", true)));
+        defs.addItem(OptionDefinitionPtr(new OptionDefinition("isc-1", 1, "isc", "empty")));
+        defs.addItem(OptionDefinitionPtr(new OptionDefinition("isc-2", 2, "isc", "ipv6-address", true)));
+
+        // Register option definitions.
+        LibDHCP::setRuntimeOptionDefs(defs);
+    }
+
+    /// @brief Initialize posix time values used in tests.
+    void initTimestamps() {
+        // Current time minus 1 hour to make sure it is in the past.
+        timestamps_["today"] = boost::posix_time::second_clock::local_time()
+            - boost::posix_time::hours(1);
+        // One second after today.
+        timestamps_["after today"] = timestamps_["today"] + boost::posix_time::seconds(1);
+        // Yesterday.
+        timestamps_["yesterday"] = timestamps_["today"] - boost::posix_time::hours(24);
+        // One second after yesterday.
+        timestamps_["after yesterday"] = timestamps_["yesterday"] + boost::posix_time::seconds(1);
+        // Two days ago.
+        timestamps_["two days ago"] = timestamps_["today"] - boost::posix_time::hours(48);
+        // Tomorrow.
+        timestamps_["tomorrow"] = timestamps_["today"] + boost::posix_time::hours(24);
+        // One second after tomorrow.
+        timestamps_["after tomorrow"] = timestamps_["tomorrow"] + boost::posix_time::seconds(1);
+    }
+
+    /// @brief Logs audit entries in the @c audit_entries_ member.
+    ///
+    /// This function is called in case of an error.
+    ///
+    /// @param server_tag Server tag for which the audit entries should be logged.
+    std::string logExistingAuditEntries(const std::string& server_tag) {
+        std::ostringstream s;
+
+        auto& mod_time_idx = audit_entries_[server_tag].get<AuditEntryModificationTimeIdTag>();
+
+        for (auto audit_entry_it = mod_time_idx.begin();
+             audit_entry_it != mod_time_idx.end();
+             ++audit_entry_it) {
+            auto audit_entry = *audit_entry_it;
+            s << audit_entry->getObjectType() << ", "
+              << audit_entry->getObjectId() << ", "
+              << static_cast<int>(audit_entry->getModificationType()) << ", "
+              << audit_entry->getModificationTime() << ", "
+              << audit_entry->getRevisionId() << ", "
+              << audit_entry->getLogMessage()
+              << std::endl;
+        }
+
+        return (s.str());
+    }
+
+    /// @brief Tests that the new audit entry is added.
+    ///
+    /// This method retrieves a collection of the existing audit entries and
+    /// checks that the new one has been added at the end of this collection.
+    /// It then verifies the values of the audit entry against the values
+    /// specified by the caller.
+    ///
+    /// @param exp_object_type Expected object type.
+    /// @param exp_modification_type Expected modification type.
+    /// @param exp_log_message Expected log message.
+    /// @param server_selector Server selector to be used for next query.
+    /// @param new_entries_num Number of the new entries expected to be inserted.
+    /// @param max_tested_entries Maximum number of entries tested.
+    void testNewAuditEntry(const std::string& exp_object_type,
+                           const AuditEntry::ModificationType& exp_modification_type,
+                           const std::string& exp_log_message,
+                           const ServerSelector& server_selector = ServerSelector::ALL(),
+                           const size_t new_entries_num = 1,
+                           const size_t max_tested_entries = 65535) {
+        // Get the server tag for which the entries are fetched.
+        std::string tag;
+        if (server_selector.getType() == ServerSelector::Type::ALL) {
+            // Server tag is 'all'.
+            tag = "all";
+
+        } else {
+            auto tags = server_selector.getTags();
+            // This test is not meant to handle multiple server tags all at once.
+            if (tags.size() > 1) {
+                ADD_FAILURE() << "Test error: do not use multiple server tags";
+
+            } else if (tags.size() == 1) {
+                // Get the server tag for which we run the current test.
+                tag = tags.begin()->get();
+            }
+        }
+
+        auto audit_entries_size_save = audit_entries_[tag].size();
+
+        // Audit entries for different server tags are stored in separate
+        // containers.
+        audit_entries_[tag] = cbptr_->getRecentAuditEntries(server_selector,
+                                                            timestamps_["two days ago"], 0);
+        ASSERT_EQ(audit_entries_size_save + new_entries_num, audit_entries_[tag].size())
+            << logExistingAuditEntries(tag);
+
+        auto& mod_time_idx = audit_entries_[tag].get<AuditEntryModificationTimeIdTag>();
+
+        // Iterate over specified number of entries starting from the most recent
+        // one and check they have correct values.
+        for (auto audit_entry_it = mod_time_idx.rbegin();
+             ((std::distance(mod_time_idx.rbegin(), audit_entry_it) < new_entries_num) &&
+              (std::distance(mod_time_idx.rbegin(), audit_entry_it) < max_tested_entries));
+             ++audit_entry_it) {
+            auto audit_entry = *audit_entry_it;
+            EXPECT_EQ(exp_object_type, audit_entry->getObjectType())
+                << logExistingAuditEntries(tag);
+            EXPECT_EQ(exp_modification_type, audit_entry->getModificationType())
+                << logExistingAuditEntries(tag);
+            EXPECT_EQ(exp_log_message, audit_entry->getLogMessage())
+                << logExistingAuditEntries(tag);
+        }
+    }
+
+    /// @brief Holds pointers to subnets used in tests.
+    std::vector<Subnet6Ptr> test_subnets_;
+
+    /// @brief Holds pointers to shared networks used in tests.
+    std::vector<SharedNetwork6Ptr> test_networks_;
+
+    /// @brief Holds pointers to option definitions used in tests.
+    std::vector<OptionDefinitionPtr> test_option_defs_;
+
+    /// @brief Holds pointers to options used in tests.
+    std::vector<OptionDescriptorPtr> test_options_;
+
+    /// @brief Holds pointers to the servers used in tests.
+    std::vector<ServerPtr> test_servers_;
+
+    /// @brief Holds timestamp values used in tests.
+    std::map<std::string, boost::posix_time::ptime> timestamps_;
+
+    /// @brief Holds pointer to the backend.
+    boost::shared_ptr<ConfigBackendDHCPv6> cbptr_;
+
+    /// @brief Holds the most recent audit entries.
+    std::map<std::string, AuditEntryCollection> audit_entries_;
+};
+
+// This test verifies that the expected backend type is returned.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getType) {
+    DatabaseConnection::ParameterMap params;
+    params["name"] = "keatest";
+    params["password"] = "keatest";
+    params["user"] = "keatest";
+    ASSERT_NO_THROW(cbptr_.reset(new PgSqlConfigBackendDHCPv6(params)));
+    EXPECT_EQ("pgsql", cbptr_->getType());
+}
+
+// This test verifies that by default localhost is returned as Postgres connection
+// host.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getHost) {
+    DatabaseConnection::ParameterMap params;
+    params["name"] = "keatest";
+    params["password"] = "keatest";
+    params["user"] = "keatest";
+    ASSERT_NO_THROW(cbptr_.reset(new PgSqlConfigBackendDHCPv6(params)));
+    EXPECT_EQ("localhost", cbptr_->getHost());
+}
+
+// This test verifies that by default port of 0 is returned as Postgres connection
+// port.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getPort) {
+    DatabaseConnection::ParameterMap params;
+    params["name"] = "keatest";
+    params["password"] = "keatest";
+    params["user"] = "keatest";
+    ASSERT_NO_THROW(cbptr_.reset(new PgSqlConfigBackendDHCPv6(params)));
+    EXPECT_EQ(0, cbptr_->getPort());
+}
+
+// This test verifies that the server can be added, updated and deleted.
+TEST_F(PgSqlConfigBackendDHCPv6Test, createUpdateDeleteServer) {
+    // Explicitly set modification time to make sure that the time
+    // returned from the database is correct.
+    test_servers_[0]->setModificationTime(timestamps_["yesterday"]);
+    test_servers_[1]->setModificationTime(timestamps_["today"]);
+
+    // Insert the server1 into the database.
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[0]));
+
+    {
+        SCOPED_TRACE("CREATE audit entry for server");
+        testNewAuditEntry("dhcp6_server",
+                          AuditEntry::ModificationType::CREATE,
+                          "server set");
+    }
+
+    // It should not be possible to create a duplicate of the logical
+    // server 'all'.
+    auto all_server = Server::create(ServerTag("all"), "this is logical server all");
+    EXPECT_THROW(cbptr_->createUpdateServer6(all_server), isc::InvalidOperation);
+
+    ServerPtr returned_server;
+
+    // An attempt to fetch the server that hasn't been inserted should return
+    // a null pointer.
+    EXPECT_NO_THROW(returned_server = cbptr_->getServer6(ServerTag("server2")));
+    EXPECT_FALSE(returned_server);
+
+    // Try to fetch the server which we expect to exist.
+    EXPECT_NO_THROW(returned_server = cbptr_->getServer6(ServerTag("server1")));
+    ASSERT_TRUE(returned_server);
+    EXPECT_EQ("server1", returned_server->getServerTagAsText());
+    EXPECT_EQ("this is server 1", returned_server->getDescription());
+    EXPECT_EQ(timestamps_["yesterday"], returned_server->getModificationTime());
+
+    // This call is expected to update the existing server.
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[1]));
+
+    {
+        SCOPED_TRACE("UPDATE audit entry for server");
+        testNewAuditEntry("dhcp6_server",
+                          AuditEntry::ModificationType::UPDATE,
+                          "server set");
+    }
+
+    // Verify that the server has been updated.
+    EXPECT_NO_THROW(returned_server = cbptr_->getServer6(ServerTag("server1")));
+    ASSERT_TRUE(returned_server);
+    EXPECT_EQ("server1", returned_server->getServerTag().get());
+    EXPECT_EQ("this is server 1 bis", returned_server->getDescription());
+    EXPECT_EQ(timestamps_["today"], returned_server->getModificationTime());
+
+
+    uint64_t servers_deleted = 0;
+
+    // Try to delete non-existing server.
+    EXPECT_NO_THROW(servers_deleted = cbptr_->deleteServer6(ServerTag("server2")));
+    EXPECT_EQ(0, servers_deleted);
+
+    // Make sure that the server1 wasn't deleted.
+    EXPECT_NO_THROW(returned_server = cbptr_->getServer6(ServerTag("server1")));
+    EXPECT_TRUE(returned_server);
+
+    // Deleting logical server 'all' is not allowed.
+    EXPECT_THROW(cbptr_->deleteServer6(ServerTag()), isc::InvalidOperation);
+
+    // Delete the existing server.
+    EXPECT_NO_THROW(servers_deleted = cbptr_->deleteServer6(ServerTag("server1")));
+    EXPECT_EQ(1, servers_deleted);
+
+    {
+        SCOPED_TRACE("DELETE audit entry for server");
+        testNewAuditEntry("dhcp6_server",
+                          AuditEntry::ModificationType::DELETE,
+                          "deleting a server");
+    }
+
+    // Make sure that the server is gone.
+    EXPECT_NO_THROW(returned_server = cbptr_->getServer6(ServerTag("server1")));
+    EXPECT_FALSE(returned_server);
+}
+
+// This test verifies that it is possible to retrieve all servers from the
+// database and then delete all of them.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getAndDeleteAllServers) {
+    for (auto i = 1; i < test_servers_.size(); ++i) {
+        EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[i]));
+    }
+
+    ServerCollection servers;
+    EXPECT_NO_THROW(servers = cbptr_->getAllServers6());
+    ASSERT_EQ(test_servers_.size() - 1, servers.size());
+
+    // All servers should have been returned.
+    EXPECT_TRUE(ServerFetcher::get(servers, ServerTag("server1")));
+    EXPECT_TRUE(ServerFetcher::get(servers, ServerTag("server2")));
+    EXPECT_TRUE(ServerFetcher::get(servers, ServerTag("server3")));
+
+    // The logical server all should not be returned. We merely return the
+    // user configured servers.
+    EXPECT_FALSE(ServerFetcher::get(servers, ServerTag()));
+
+    // Delete all servers and make sure they are gone.
+    uint64_t deleted_servers = 0;
+    EXPECT_NO_THROW(deleted_servers = cbptr_->deleteAllServers6());
+
+    EXPECT_NO_THROW(servers = cbptr_->getAllServers6());
+    EXPECT_TRUE(servers.empty());
+
+    // All servers should be gone.
+    EXPECT_FALSE(ServerFetcher::get(servers, ServerTag("server1")));
+    EXPECT_FALSE(ServerFetcher::get(servers, ServerTag("server2")));
+    EXPECT_FALSE(ServerFetcher::get(servers, ServerTag("server3")));
+
+    // The number of deleted server should be equal to the number of
+    // inserted servers. The logical 'all' server should be excluded.
+    EXPECT_EQ(test_servers_.size() - 1, deleted_servers);
+}
+
+// This test verifies that the global parameter can be added, updated and
+// deleted.
+TEST_F(PgSqlConfigBackendDHCPv6Test, createUpdateDeleteGlobalParameter6) {
+    StampedValuePtr global_parameter = StampedValue::create("global", "whale");
+
+    // Explicitly set modification time to make sure that the time
+    // returned from the database is correct.
+    global_parameter->setModificationTime(timestamps_["yesterday"]);
+    cbptr_->createUpdateGlobalParameter6(ServerSelector::ALL(),
+                                         global_parameter);
+
+    {
+        SCOPED_TRACE("CREATE audit entry for global parameter");
+        testNewAuditEntry("dhcp6_global_parameter",
+                          AuditEntry::ModificationType::CREATE,
+                          "global parameter set");
+    }
+
+    // Verify returned parameter and the modification time.
+    StampedValuePtr returned_global_parameter =
+        cbptr_->getGlobalParameter6(ServerSelector::ALL(), "global");
+    ASSERT_TRUE(returned_global_parameter);
+    EXPECT_EQ("global", returned_global_parameter->getName());
+    EXPECT_EQ("whale", returned_global_parameter->getValue());
+    EXPECT_TRUE(returned_global_parameter->getModificationTime() ==
+                global_parameter->getModificationTime());
+    ASSERT_EQ(1, returned_global_parameter->getServerTags().size());
+    EXPECT_EQ("all", returned_global_parameter->getServerTags().begin()->get());
+
+    // Because we have added the global parameter for all servers, it
+    // should be also returned for the explicitly specified server.
+    returned_global_parameter = cbptr_->getGlobalParameter6(ServerSelector::ONE("server1"),
+                                                            "global");
+    ASSERT_TRUE(returned_global_parameter);
+    EXPECT_EQ("global", returned_global_parameter->getName());
+    EXPECT_EQ("whale", returned_global_parameter->getValue());
+    EXPECT_TRUE(returned_global_parameter->getModificationTime() ==
+                global_parameter->getModificationTime());
+    ASSERT_EQ(1, returned_global_parameter->getServerTags().size());
+    EXPECT_EQ("all", returned_global_parameter->getServerTags().begin()->get());
+
+    // Check that the parameter is updated when selector is specified correctly.
+    global_parameter = StampedValue::create("global", "fish");
+    cbptr_->createUpdateGlobalParameter6(ServerSelector::ALL(),
+                                         global_parameter);
+    returned_global_parameter = cbptr_->getGlobalParameter6(ServerSelector::ALL(),
+                                                            "global");
+    ASSERT_TRUE(returned_global_parameter);
+    EXPECT_EQ("global", returned_global_parameter->getName());
+    EXPECT_EQ("fish", returned_global_parameter->getValue());
+    EXPECT_TRUE(returned_global_parameter->getModificationTime() ==
+                global_parameter->getModificationTime());
+
+    {
+        SCOPED_TRACE("UPDATE audit entry for the global parameter");
+        testNewAuditEntry("dhcp6_global_parameter",
+                          AuditEntry::ModificationType::UPDATE,
+                          "global parameter set");
+    }
+
+    // Should not delete parameter specified for all servers if explicit
+    // server name is provided.
+    EXPECT_EQ(0, cbptr_->deleteGlobalParameter6(ServerSelector::ONE("server1"),
+                                                "global"));
+
+    // Delete parameter and make sure it is gone.
+    cbptr_->deleteGlobalParameter6(ServerSelector::ALL(), "global");
+    returned_global_parameter = cbptr_->getGlobalParameter6(ServerSelector::ALL(),
+                                                            "global");
+    EXPECT_FALSE(returned_global_parameter);
+
+    {
+        SCOPED_TRACE("DELETE audit entry for the global parameter");
+        testNewAuditEntry("dhcp6_global_parameter",
+                          AuditEntry::ModificationType::DELETE,
+                          "global parameter deleted");
+    }
+}
+
+// This test verifies that it is possible to differentiate between the
+// global parameters by server tag and that the value specified for the
+// particular server overrides the value specified for all servers.
+TEST_F(PgSqlConfigBackendDHCPv6Test, globalParameters6WithServerTags) {
+    // Create three global parameters having the same name.
+    StampedValuePtr global_parameter1 = StampedValue::create("global", "value1");
+    StampedValuePtr global_parameter2 = StampedValue::create("global", "value2");
+    StampedValuePtr global_parameter3 = StampedValue::create("global", "value3");
+
+    // Try to insert one of them and associate with non-existing server.
+    // This should fail because the server must be inserted first.
+    EXPECT_THROW(cbptr_->createUpdateGlobalParameter6(ServerSelector::ONE("server1"),
+                                                      global_parameter1),
+                 NullKeyError);
+
+    // Create two servers.
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[1]));
+    {
+        SCOPED_TRACE("server1 is created");
+        testNewAuditEntry("dhcp6_server",
+                          AuditEntry::ModificationType::CREATE,
+                          "server set");
+    }
+
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[2]));
+    {
+        SCOPED_TRACE("server2 is created");
+        testNewAuditEntry("dhcp6_server",
+                          AuditEntry::ModificationType::CREATE,
+                          "server set");
+    }
+
+    // This time inserting the global parameters for the server1 and server2 should
+    // be successful.
+    EXPECT_NO_THROW(cbptr_->createUpdateGlobalParameter6(ServerSelector::ONE("server1"),
+                                                         global_parameter1));
+    {
+        SCOPED_TRACE("Global parameter for server1 is set");
+        // The value of 3 means there should be 3 audit entries available for the
+        // server1, two that indicate creation of the servers and one that we
+        // validate, which sets the global value.
+        testNewAuditEntry("dhcp6_global_parameter",
+                          AuditEntry::ModificationType::CREATE,
+                          "global parameter set",
+                          ServerSelector::ONE("server1"),
+                          3, 1);
+    }
+
+
+    EXPECT_NO_THROW(cbptr_->createUpdateGlobalParameter6(ServerSelector::ONE("server2"),
+                                                         global_parameter2));
+    {
+        SCOPED_TRACE("Global parameter for server2 is set");
+        // Same as in case of the server2, there should be 3 audit entries of
+        // which one we validate.
+        testNewAuditEntry("dhcp6_global_parameter",
+                          AuditEntry::ModificationType::CREATE,
+                          "global parameter set",
+                          ServerSelector::ONE("server2"),
+                          3, 1);
+    }
+
+    // The last parameter is associated with all servers.
+    EXPECT_NO_THROW(cbptr_->createUpdateGlobalParameter6(ServerSelector::ALL(),
+                                                         global_parameter3));
+    {
+        SCOPED_TRACE("Global parameter for all servers is set");
+        // There should be one new audit entry for all servers. It indicates
+        // the insertion of the global value.
+        testNewAuditEntry("dhcp6_global_parameter",
+                          AuditEntry::ModificationType::CREATE,
+                          "global parameter set",
+                          ServerSelector::ALL(),
+                          1, 1);
+    }
+
+    StampedValuePtr returned_global;
+
+    // Try to fetch the value specified for all servers.
+    EXPECT_NO_THROW(
+        returned_global = cbptr_->getGlobalParameter6(ServerSelector::ALL(),
+                                                      "global")
+    );
+    ASSERT_TRUE(returned_global);
+    EXPECT_EQ(global_parameter3->getValue(), returned_global->getValue());
+    ASSERT_EQ(1, returned_global->getServerTags().size());
+    EXPECT_EQ("all", returned_global->getServerTags().begin()->get());
+
+    // Try to fetch the value specified for the server1. This should override the
+    // value specified for all servers.
+    EXPECT_NO_THROW(
+        returned_global = cbptr_->getGlobalParameter6(ServerSelector::ONE("server1"),
+                                                      "global")
+    );
+    ASSERT_TRUE(returned_global);
+    EXPECT_EQ(global_parameter1->getValue(), returned_global->getValue());
+
+    ASSERT_EQ(1, returned_global->getServerTags().size());
+    EXPECT_EQ("server1", returned_global->getServerTags().begin()->get());
+
+    // The same in case of the server2.
+    EXPECT_NO_THROW(
+        returned_global = cbptr_->getGlobalParameter6(ServerSelector::ONE("server2"),
+                                                      "global")
+    );
+    ASSERT_TRUE(returned_global);
+    EXPECT_EQ(global_parameter2->getValue(), returned_global->getValue());
+    ASSERT_EQ(1, returned_global->getServerTags().size());
+    EXPECT_EQ("server2", returned_global->getServerTags().begin()->get());
+
+    StampedValueCollection returned_globals;
+
+    // Try to fetch the collection of globals for the server1, server2 and server3.
+    // The server3 does not have an explicit value so for this server we should get
+    /// the value for 'all'.
+    EXPECT_NO_THROW(
+        returned_globals = cbptr_->getAllGlobalParameters6(ServerSelector::
+                                                           MULTIPLE({ "server1", "server2",
+                                                                      "server3" }));
+    );
+    ASSERT_EQ(3, returned_globals.size());
+
+    // Capture the returned values into the map so as we can check the
+    // values against the servers.
+    std::map<std::string, std::string> values;
+    for (auto g = returned_globals.begin(); g != returned_globals.end(); ++g) {
+        ASSERT_EQ(1, (*g)->getServerTags().size());
+        values[(*g)->getServerTags().begin()->get()] = ((*g)->getValue());
+    }
+
+    ASSERT_EQ(3, values.size());
+    EXPECT_EQ(global_parameter1->getValue(), values["server1"]);
+    EXPECT_EQ(global_parameter2->getValue(), values["server2"]);
+    EXPECT_EQ(global_parameter3->getValue(), values["all"]);
+
+    // Try to fetch the collection of global parameters specified for all servers.
+    // This excludes the values specific to server1 and server2. It returns only the
+    // common ones.
+    EXPECT_NO_THROW(
+        returned_globals = cbptr_->getAllGlobalParameters6(ServerSelector::ALL())
+    );
+    ASSERT_EQ(1, returned_globals.size());
+    returned_global = *returned_globals.begin();
+    EXPECT_EQ(global_parameter3->getValue(), returned_global->getValue());
+    ASSERT_EQ(1, returned_global->getServerTags().size());
+    EXPECT_EQ("all", returned_global->getServerTags().begin()->get());
+
+    // Delete the server1. It should remove associations of this server with the
+    // global parameter and the global parameter itself.
+    EXPECT_NO_THROW(cbptr_->deleteServer6(ServerTag("server1")));
+    EXPECT_NO_THROW(
+        returned_globals = cbptr_->getAllGlobalParameters6(ServerSelector::ONE("server1"))
+    );
+    ASSERT_EQ(1, returned_globals.size());
+    returned_global = *returned_globals.begin();
+    // As a result, the value fetched for the server1 should be the one available for
+    // all servers, rather than the one dedicated for server1. The association of
+    // the server1 specific value with the server1 should be gone.
+    EXPECT_EQ(global_parameter3->getValue(), returned_global->getValue());
+    ASSERT_EQ(1, returned_global->getServerTags().size());
+    EXPECT_EQ("all", returned_global->getServerTags().begin()->get());
+
+    {
+        SCOPED_TRACE("DELETE audit entry for the global parameter after server deletion");
+        // We expect two new audit entries for the server1, one indicating that the
+        // server has been deleted and another one indicating that the corresponding
+        // global value has been deleted. We check the latter entry.
+        testNewAuditEntry("dhcp6_global_parameter",
+                          AuditEntry::ModificationType::DELETE,
+                          "deleting a server", ServerSelector::ONE("server1"),
+                          2, 1);
+    }
+
+    // Attempt to delete global parameter for server1.
+    uint64_t deleted_num = 0;
+    EXPECT_NO_THROW(deleted_num = cbptr_->deleteGlobalParameter6(ServerSelector::ONE("server1"),
+                                                                 "global"));
+    // No parameters should be deleted. In particular, the parameter for the logical
+    // server 'all' should not be deleted.
+    EXPECT_EQ(0, deleted_num);
+
+    // Deleting the existing value for server2 should succeed.
+    EXPECT_NO_THROW(deleted_num = cbptr_->deleteGlobalParameter6(ServerSelector::ONE("server2"),
+                                                                 "global"));
+    EXPECT_EQ(1, deleted_num);
+
+    // Create it again to test that deletion of all server removes this too.
+    EXPECT_NO_THROW(cbptr_->createUpdateGlobalParameter6(ServerSelector::ONE("server2"),
+                                                         global_parameter2));
+
+    // Delete all servers, except 'all'.
+    EXPECT_NO_THROW(deleted_num = cbptr_->deleteAllServers6());
+    EXPECT_NO_THROW(
+        returned_globals = cbptr_->getAllGlobalParameters6(ServerSelector::ALL())
+    );
+    EXPECT_EQ(1, deleted_num);
+    ASSERT_EQ(1, returned_globals.size());
+    returned_global = *returned_globals.begin();
+    // The common value for all servers should still be available because 'all'
+    // logical server should not be deleted.
+    EXPECT_EQ(global_parameter3->getValue(), returned_global->getValue());
+    ASSERT_EQ(1, returned_global->getServerTags().size());
+    EXPECT_EQ("all", returned_global->getServerTags().begin()->get());
+
+    {
+        SCOPED_TRACE("DELETE audit entry for the global parameter after deletion of"
+                     " all servers");
+        // There should be 4 new audit entries. One for deleting the global, one for
+        // re-creating it, one for deleting the server2 and one for deleting the
+        // global again as a result of deleting the server2.
+        testNewAuditEntry("dhcp6_global_parameter",
+                          AuditEntry::ModificationType::DELETE,
+                          "deleting all servers", ServerSelector::ONE("server2"),
+                          4, 1);
+    }
+}
+
+// This test verifies that all global parameters can be retrieved and deleted.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getAllGlobalParameters6) {
+    // Create 3 parameters and put them into the database.
+    cbptr_->createUpdateGlobalParameter6(ServerSelector::ALL(),
+        StampedValue::create("name1", "value1"));
+    cbptr_->createUpdateGlobalParameter6(ServerSelector::ALL(),
+        StampedValue::create("name2", Element::create(static_cast<int64_t>(65))));
+    cbptr_->createUpdateGlobalParameter6(ServerSelector::ALL(),
+        StampedValue::create("name3", "value3"));
+    cbptr_->createUpdateGlobalParameter6(ServerSelector::ALL(),
+        StampedValue::create("name4", Element::create(static_cast<bool>(true))));
+    cbptr_->createUpdateGlobalParameter6(ServerSelector::ALL(),
+        StampedValue::create("name5", Element::create(static_cast<double>(1.65))));
+
+    // Fetch all parameters.
+    auto parameters = cbptr_->getAllGlobalParameters6(ServerSelector::ALL());
+    ASSERT_EQ(5, parameters.size());
+
+    const auto& parameters_index = parameters.get<StampedValueNameIndexTag>();
+
+    for (auto param = parameters_index.begin(); param != parameters_index.end();
+         ++param) {
+        ASSERT_EQ(1, (*param)->getServerTags().size());
+        EXPECT_EQ("all", (*param)->getServerTags().begin()->get());
+    }
+
+    // Verify their values.
+    EXPECT_EQ("value1", (*parameters_index.find("name1"))->getValue());
+    EXPECT_EQ(65, (*parameters_index.find("name2"))->getIntegerValue());
+    EXPECT_EQ("value3", (*parameters_index.find("name3"))->getValue());
+    EXPECT_TRUE((*parameters_index.find("name4"))->getBoolValue());
+    EXPECT_EQ(1.65, (*parameters_index.find("name5"))->getDoubleValue());
+
+    // Should be able to fetch these parameters when explicitly providing
+    // the server tag.
+    parameters = cbptr_->getAllGlobalParameters6(ServerSelector::ONE("server1"));
+    EXPECT_EQ(5, parameters.size());
+
+    // Deleting global parameters with non-matching server selector
+    // should fail.
+    EXPECT_EQ(0, cbptr_->deleteAllGlobalParameters6(ServerSelector::ONE("server1")));
+
+    // Delete all parameters and make sure they are gone.
+    EXPECT_EQ(5, cbptr_->deleteAllGlobalParameters6(ServerSelector::ALL()));
+    parameters = cbptr_->getAllGlobalParameters6(ServerSelector::ALL());
+    EXPECT_TRUE(parameters.empty());
+}
+
+// This test verifies that modified global parameters can be retrieved.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getModifiedGlobalParameters6) {
+    // Create 3 global parameters and assign modification times:
+    // "yesterday", "today" and "tomorrow" respectively.
+    StampedValuePtr value = StampedValue::create("name1", "value1");
+    value->setModificationTime(timestamps_["yesterday"]);
+    cbptr_->createUpdateGlobalParameter6(ServerSelector::ALL(),
+                                         value);
+
+    value = StampedValue::create("name2", Element::create(static_cast<int64_t>(65)));
+    value->setModificationTime(timestamps_["today"]);
+    cbptr_->createUpdateGlobalParameter6(ServerSelector::ALL(),
+                                         value);
+
+    value = StampedValue::create("name3", "value3");
+    value->setModificationTime(timestamps_["tomorrow"]);
+    cbptr_->createUpdateGlobalParameter6(ServerSelector::ALL(),
+                                         value);
+
+    // Get parameters modified after "today".
+    auto parameters = cbptr_->getModifiedGlobalParameters6(ServerSelector::ALL(),
+                                                           timestamps_["after today"]);
+
+    const auto& parameters_index = parameters.get<StampedValueNameIndexTag>();
+
+    // It should be the one modified "tomorrow".
+    ASSERT_EQ(1, parameters_index.size());
+
+    auto parameter = parameters_index.find("name3");
+    ASSERT_FALSE(parameter == parameters_index.end());
+
+    ASSERT_TRUE(*parameter);
+    EXPECT_EQ("value3", (*parameter)->getValue());
+
+    // Should be able to fetct these parameters when explicitly providing
+    // the server tag.
+    parameters = cbptr_->getModifiedGlobalParameters6(ServerSelector::ONE("server1"),
+                                                      timestamps_["after today"]);
+    EXPECT_EQ(1, parameters.size());
+}
+
+// Test that the NullKeyError message is correctly updated.
+TEST_F(PgSqlConfigBackendDHCPv6Test, nullKeyError) {
+    // Create a global parameter (it should work with any object type).
+    StampedValuePtr global_parameter = StampedValue::create("global", "value");
+
+    // Try to insert it and associate with non-existing server.
+    std::string msg;
+    try {
+        cbptr_->createUpdateGlobalParameter6(ServerSelector::ONE("server1"),
+                                             global_parameter);
+        msg = "got no exception";
+    } catch (const NullKeyError& ex) {
+        msg = ex.what();
+    } catch (const std::exception&) {
+        msg = "got another exception";
+    }
+    EXPECT_EQ("server 'server1' does not exist", msg);
+}
+
+// Test that ceateUpdateSubnet6 throws appropriate exceptions for various
+// server selectors.
+TEST_F(PgSqlConfigBackendDHCPv6Test, createUpdateSubnet6Selectors) {
+    ASSERT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[0]));
+    ASSERT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[2]));
+
+    // Supported selectors.
+    Subnet6Ptr subnet = test_subnets_[0];
+    EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ALL(),
+                                                subnet));
+    subnet = test_subnets_[2];
+    EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ONE("server1"),
+                                                subnet));
+    subnet = test_subnets_[3];
+    EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                                subnet));
+
+    // Not supported server selectors.
+    EXPECT_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ANY(), subnet),
+                 isc::InvalidOperation);
+
+    // Not implemented server selectors.
+    EXPECT_THROW(cbptr_->createUpdateSubnet6(ServerSelector::UNASSIGNED(),
+                                             subnet),
+                 isc::NotImplemented);
+}
+
+// Test that subnet can be inserted, fetched, updated and then fetched again.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getSubnet6) {
+    // Insert the server2 into the database.
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[2]));
+    {
+        SCOPED_TRACE("CREATE audit entry for server");
+        testNewAuditEntry("dhcp6_server",
+                          AuditEntry::ModificationType::CREATE,
+                          "server set");
+    }
+
+    auto subnet = test_subnets_[0];
+    auto subnet2 = test_subnets_[2];
+
+    // An attempt to add a subnet to a non-existing server (server1) should fail.
+    EXPECT_THROW(cbptr_->createUpdateSubnet6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                             subnet2),
+                 NullKeyError);
+
+    // The subnet shouldn't have been added, even though one of the servers exists.
+    Subnet6Ptr returned_subnet;
+    ASSERT_NO_THROW(returned_subnet = cbptr_->getSubnet6(ServerSelector::ONE("server2"),
+                                                                             subnet2->getID()));
+    EXPECT_FALSE(returned_subnet);
+
+    // Insert two subnets, one for all servers and one for server2.
+    EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ALL(), subnet));
+    {
+        SCOPED_TRACE("CREATE audit entry for the subnet");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::CREATE,
+                          "subnet set");
+    }
+
+
+    EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ONE("server2"), subnet2));
+    {
+        SCOPED_TRACE("CREATE audit entry for the subnet");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::CREATE,
+                          "subnet set", ServerSelector::ONE("subnet2"),
+                          2, 1);
+    }
+
+    // We are not going to support selection of a single entry for multiple servers.
+    EXPECT_THROW(cbptr_->getSubnet6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                    subnet->getID()),
+                 isc::InvalidOperation);
+
+    EXPECT_THROW(cbptr_->getSubnet6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                    subnet->toText()),
+                 isc::InvalidOperation);
+
+    // Test that this subnet will be fetched for various server selectors.
+    auto test_get_subnet = [this, &subnet] (const std::string& test_case_name,
+                                            const ServerSelector& server_selector,
+                                            const std::string& expected_tag = ServerTag::ALL) {
+        SCOPED_TRACE(test_case_name);
+
+        // Test fetching subnet by id.
+        Subnet6Ptr returned_subnet;
+        ASSERT_NO_THROW(returned_subnet = cbptr_->getSubnet6(server_selector, subnet->getID()));
+        ASSERT_TRUE(returned_subnet);
+
+        ASSERT_EQ(1, returned_subnet->getServerTags().size());
+        EXPECT_TRUE(returned_subnet->hasServerTag(ServerTag(expected_tag)));
+
+        EXPECT_EQ(subnet->toElement()->str(), returned_subnet->toElement()->str());
+
+        // Test fetching subnet by prefix.
+        ASSERT_NO_THROW(returned_subnet = cbptr_->getSubnet6(server_selector,
+                                                             subnet->toText()));
+        ASSERT_TRUE(returned_subnet);
+
+        ASSERT_EQ(1, returned_subnet->getServerTags().size());
+        EXPECT_TRUE(returned_subnet->hasServerTag(ServerTag(expected_tag)));
+
+        EXPECT_EQ(subnet->toElement()->str(), returned_subnet->toElement()->str());
+    };
+
+    {
+        SCOPED_TRACE("testing various server selectors before update");
+        test_get_subnet("all servers", ServerSelector::ALL());
+        test_get_subnet("one server", ServerSelector::ONE("server1"));
+        test_get_subnet("any server", ServerSelector::ANY());
+    }
+
+    subnet = subnet2;
+    {
+        SCOPED_TRACE("testing server selectors for another server");
+        test_get_subnet("one server", ServerSelector::ONE("server2"), "server2");
+        test_get_subnet("any server", ServerSelector::ANY(), "server2");
+    }
+
+    // Update the subnet in the database (both use the same ID).
+    subnet = test_subnets_[1];
+    EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ALL(), subnet));
+    {
+        SCOPED_TRACE("CREATE audit entry for the subnet");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::UPDATE,
+                          "subnet set");
+    }
+
+    {
+        SCOPED_TRACE("testing various server selectors after update");
+        test_get_subnet("all servers", ServerSelector::ALL());
+        test_get_subnet("one server", ServerSelector::ONE("server1"));
+        test_get_subnet("any server", ServerSelector::ANY());
+    }
+
+    // The server2 specific subnet should not be returned if the server selector
+    // is not matching.
+    EXPECT_FALSE(cbptr_->getSubnet6(ServerSelector::ALL(), subnet2->getID()));
+    EXPECT_FALSE(cbptr_->getSubnet6(ServerSelector::ALL(), subnet2->toText()));
+    EXPECT_FALSE(cbptr_->getSubnet6(ServerSelector::ONE("server1"), subnet2->getID()));
+    EXPECT_FALSE(cbptr_->getSubnet6(ServerSelector::ONE("server1"), subnet2->toText()));
+
+    // Update the subnet in the database (both use the same prefix).
+    subnet2.reset(new Subnet6(IOAddress("2001:db8:3::"),
+                              64, 30, 40, 50, 80, 8192));
+    EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ONE("server2"),  subnet2));
+
+    // Fetch again and verify.
+    returned_subnet = cbptr_->getSubnet6(ServerSelector::ONE("server2"), subnet2->toText());
+    ASSERT_TRUE(returned_subnet);
+    EXPECT_EQ(subnet2->toElement()->str(), returned_subnet->toElement()->str());
+
+    // Update the subnet when it conflicts same id and same prefix both
+    // with different subnets. This should throw.
+    // Subnets are 2001:db8:1::/48 id 1024 and 2001:db8:3::/64 id 8192
+    subnet2.reset(new Subnet6(IOAddress("2001:db8:1::"),
+                              48, 30, 40, 50, 80, 8192));
+    EXPECT_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ONE("server2"),  subnet2),
+                 DuplicateEntry);
+}
+
+// Test that getSubnet6 by ID throws appropriate exceptions for various server
+// selectors.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getSubnet6byIdSelectors) {
+    // Supported selectors.
+    EXPECT_NO_THROW(cbptr_->getSubnet6(ServerSelector::ANY(), SubnetID(1)));
+    EXPECT_NO_THROW(cbptr_->getSubnet6(ServerSelector::UNASSIGNED(), SubnetID(1)));
+    EXPECT_NO_THROW(cbptr_->getSubnet6(ServerSelector::ALL(), SubnetID(1)));
+    EXPECT_NO_THROW(cbptr_->getSubnet6(ServerSelector::ONE("server1"), SubnetID(1)));
+
+    // Not supported selectors.
+    EXPECT_THROW(cbptr_->getSubnet6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                    SubnetID(1)),
+                 isc::InvalidOperation);
+}
+
+// Test that the information about unspecified optional parameters gets
+// propagated to the database.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getSubnet6WithOptionalUnspecified) {
+    // Create a subnet and wrap it within a shared network. It is important
+    // to have the shared network to verify that the subnet doesn't inherit
+    // the values of the shared network but stores the NULL values in the
+    // for those parameters that are unspecified on the subnet level.
+    Subnet6Ptr subnet = test_subnets_[2];
+    SharedNetwork6Ptr shared_network = test_networks_[0];
+    shared_network->add(subnet);
+
+    // Need to add the shared network to the database because otherwise
+    // the subnet foreign key would fail.
+    cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(), shared_network);
+    cbptr_->createUpdateSubnet6(ServerSelector::ALL(), subnet);
+
+    // Fetch this subnet by subnet identifier.
+    Subnet6Ptr returned_subnet = cbptr_->getSubnet6(ServerSelector::ALL(),
+                                                    subnet->getID());
+    ASSERT_TRUE(returned_subnet);
+
+    EXPECT_TRUE(returned_subnet->getIface().unspecified());
+    EXPECT_TRUE(returned_subnet->getIface().empty());
+
+    EXPECT_TRUE(returned_subnet->getClientClass().unspecified());
+    EXPECT_TRUE(returned_subnet->getClientClass().empty());
+
+    EXPECT_TRUE(returned_subnet->getValid().unspecified());
+    EXPECT_EQ(0, returned_subnet->getValid().get());
+
+    EXPECT_TRUE(returned_subnet->getPreferred().unspecified());
+    EXPECT_EQ(0, returned_subnet->getPreferred().get());
+
+    EXPECT_TRUE(returned_subnet->getT1().unspecified());
+    EXPECT_EQ(0, returned_subnet->getT1().get());
+
+    EXPECT_TRUE(returned_subnet->getT2().unspecified());
+    EXPECT_EQ(0, returned_subnet->getT2().get());
+
+    EXPECT_TRUE(returned_subnet->getReservationsGlobal().unspecified());
+    EXPECT_FALSE(returned_subnet->getReservationsGlobal().get());
+
+    EXPECT_TRUE(returned_subnet->getReservationsInSubnet().unspecified());
+    EXPECT_TRUE(returned_subnet->getReservationsInSubnet().get());
+
+    EXPECT_TRUE(returned_subnet->getReservationsOutOfPool().unspecified());
+    EXPECT_FALSE(returned_subnet->getReservationsOutOfPool().get());
+
+    EXPECT_TRUE(returned_subnet->getCalculateTeeTimes().unspecified());
+    EXPECT_FALSE(returned_subnet->getCalculateTeeTimes().get());
+
+    EXPECT_TRUE(returned_subnet->getT1Percent().unspecified());
+    EXPECT_EQ(0.0, returned_subnet->getT1Percent().get());
+
+    EXPECT_TRUE(returned_subnet->getT2Percent().unspecified());
+    EXPECT_EQ(0.0, returned_subnet->getT2Percent().get());
+
+    EXPECT_TRUE(returned_subnet->getRapidCommit().unspecified());
+    EXPECT_FALSE(returned_subnet->getRapidCommit().get());
+
+    EXPECT_FALSE(returned_subnet->getDdnsSendUpdates().unspecified());
+    EXPECT_TRUE(returned_subnet->getDdnsSendUpdates().get());
+
+    EXPECT_FALSE(returned_subnet->getDdnsOverrideNoUpdate().unspecified());
+    EXPECT_TRUE(returned_subnet->getDdnsOverrideNoUpdate().get());
+
+    EXPECT_FALSE(returned_subnet->getDdnsOverrideClientUpdate().unspecified());
+    EXPECT_FALSE(returned_subnet->getDdnsOverrideClientUpdate().get());
+
+    EXPECT_FALSE(returned_subnet->getDdnsReplaceClientNameMode().unspecified());
+    EXPECT_EQ(D2ClientConfig::ReplaceClientNameMode::RCM_WHEN_PRESENT,
+              returned_subnet->getDdnsReplaceClientNameMode().get());
+
+    EXPECT_FALSE(returned_subnet->getDdnsGeneratedPrefix().unspecified());
+    EXPECT_EQ("myhost", returned_subnet->getDdnsGeneratedPrefix().get());
+
+    EXPECT_FALSE(returned_subnet->getDdnsQualifyingSuffix().unspecified());
+    EXPECT_EQ("example.org", returned_subnet->getDdnsQualifyingSuffix().get());
+
+    // The easiest way to verify whether the returned subnet matches the inserted
+    // subnet is to convert both to text.
+    EXPECT_EQ(subnet->toElement()->str(), returned_subnet->toElement()->str());
+
+}
+
+// Test that subnet can be associated with a shared network.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getSubnet6SharedNetwork) {
+    Subnet6Ptr subnet = test_subnets_[0];
+    SharedNetwork6Ptr shared_network = test_networks_[0];
+
+    // Add subnet to a shared network.
+    shared_network->add(subnet);
+
+    // Store shared network in the database.
+    cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(),
+                                       shared_network);
+
+    // Store subnet associated with the shared network in the database.
+    cbptr_->createUpdateSubnet6(ServerSelector::ALL(), subnet);
+
+    // Fetch this subnet by subnet identifier.
+    Subnet6Ptr returned_subnet = cbptr_->getSubnet6(ServerSelector::ALL(),
+                                                    test_subnets_[0]->getID());
+    ASSERT_TRUE(returned_subnet);
+    ASSERT_EQ(1, returned_subnet->getServerTags().size());
+    EXPECT_EQ("all", returned_subnet->getServerTags().begin()->get());
+
+    // The easiest way to verify whether the returned subnet matches the inserted
+    // subnet is to convert both to text.
+    EXPECT_EQ(subnet->toElement()->str(), returned_subnet->toElement()->str());
+
+    // However, the check above doesn't verify whether shared network name was
+    // correctly returned from the database.
+    EXPECT_EQ(shared_network->getName(), returned_subnet->getSharedNetworkName());
+}
+
+// Test that subnet can be fetched by prefix.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getSubnet6ByPrefix) {
+    // Insert subnet to the database.
+    Subnet6Ptr subnet = test_subnets_[0];
+    cbptr_->createUpdateSubnet6(ServerSelector::ALL(), subnet);
+
+    // Fetch the subnet by prefix.
+    Subnet6Ptr returned_subnet = cbptr_->getSubnet6(ServerSelector::ALL(),
+                                                    "2001:db8::/64");
+    ASSERT_TRUE(returned_subnet);
+    ASSERT_EQ(1, returned_subnet->getServerTags().size());
+    EXPECT_EQ("all", returned_subnet->getServerTags().begin()->get());
+
+    // Verify subnet contents.
+    EXPECT_EQ(subnet->toElement()->str(), returned_subnet->toElement()->str());
+
+    // Fetching the subnet for an explicitly specified server tag should
+    // succeed too.
+    returned_subnet = cbptr_->getSubnet6(ServerSelector::ONE("server1"),
+                                         "2001:db8::/64");
+    EXPECT_EQ(subnet->toElement()->str(), returned_subnet->toElement()->str());
+}
+
+// Test that getSubnet6 by prefix throws appropriate exceptions for various server
+// selectors.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getSubnet6byPrefixSelectors) {
+    // Supported selectors.
+    EXPECT_NO_THROW(cbptr_->getSubnet6(ServerSelector::ANY(), "192.0.2.0/26"));
+    EXPECT_NO_THROW(cbptr_->getSubnet6(ServerSelector::UNASSIGNED(), "192.0.2.0/26"));
+    EXPECT_NO_THROW(cbptr_->getSubnet6(ServerSelector::ALL(), "192.0.2.0/26"));
+    EXPECT_NO_THROW(cbptr_->getSubnet6(ServerSelector::ONE("server1"), "192.0.2.0/26"));
+
+    // Not supported selectors.
+    EXPECT_THROW(cbptr_->getSubnet6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                    "192.0.2.0/26"),
+                 isc::InvalidOperation);
+}
+
+// Test that all subnets can be fetched and then deleted.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getAllSubnets6) {
+    // Insert test subnets into the database. Note that the second subnet will
+    // overwrite the first subnet as they use the same ID.
+    for (auto subnet : test_subnets_) {
+        cbptr_->createUpdateSubnet6(ServerSelector::ALL(), subnet);
+
+        // That subnet overrides the first subnet so the audit entry should
+        // indicate an update.
+        if (subnet->toText() == "2001:db8:1::/48") {
+            SCOPED_TRACE("UPDATE audit entry for the subnet " + subnet->toText());
+            testNewAuditEntry("dhcp6_subnet",
+                              AuditEntry::ModificationType::UPDATE,
+                              "subnet set");
+
+        } else {
+            SCOPED_TRACE("CREATE audit entry for the subnet " + subnet->toText());
+            testNewAuditEntry("dhcp6_subnet",
+                              AuditEntry::ModificationType::CREATE,
+                              "subnet set");
+        }
+    }
+
+    // Fetch all subnets.
+    Subnet6Collection subnets = cbptr_->getAllSubnets6(ServerSelector::ALL());
+    ASSERT_EQ(test_subnets_.size() - 1, subnets.size());
+
+    // All subnets should also be returned for explicitly specified server tag.
+    subnets = cbptr_->getAllSubnets6(ServerSelector::ONE("server1"));
+    ASSERT_EQ(test_subnets_.size() - 1, subnets.size());
+
+    // See if the subnets are returned ok.
+    auto subnet_it = subnets.begin();
+    for (auto i = 0; i < subnets.size(); ++i, ++subnet_it) {
+        EXPECT_EQ(test_subnets_[i + 1]->toElement()->str(),
+                  (*subnet_it)->toElement()->str());
+        ASSERT_EQ(1, (*subnet_it)->getServerTags().size());
+        EXPECT_EQ("all", (*subnet_it)->getServerTags().begin()->get());
+    }
+
+    // Attempt to remove the non existing subnet should  return 0.
+    EXPECT_EQ(0, cbptr_->deleteSubnet6(ServerSelector::ALL(), 22));
+    EXPECT_EQ(0, cbptr_->deleteSubnet6(ServerSelector::ALL(),
+                                       "2001:db8:555::/64"));
+    // All subnets should be still there.
+    ASSERT_EQ(test_subnets_.size() - 1, subnets.size());
+
+    // Should not delete the subnet for explicit server tag because
+    // our subnet is for all servers.
+    EXPECT_EQ(0, cbptr_->deleteSubnet6(ServerSelector::ONE("server1"),
+                                       test_subnets_[1]->getID()));
+
+    // Also, verify that behavior when deleting by prefix.
+    EXPECT_EQ(0, cbptr_->deleteSubnet6(ServerSelector::ONE("server1"),
+                                       test_subnets_[2]->toText()));
+
+    // Same for all subnets.
+    EXPECT_EQ(0, cbptr_->deleteAllSubnets6(ServerSelector::ONE("server1")));
+
+    // Delete first subnet by id and verify that it is gone.
+    EXPECT_EQ(1, cbptr_->deleteSubnet6(ServerSelector::ALL(),
+                                       test_subnets_[1]->getID()));
+
+    {
+        SCOPED_TRACE("DELETE first subnet audit entry");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::DELETE,
+                          "subnet deleted");
+    }
+
+    subnets = cbptr_->getAllSubnets6(ServerSelector::ALL());
+    ASSERT_EQ(test_subnets_.size() - 2, subnets.size());
+
+    // Delete second subnet by prefix and verify it is gone.
+    EXPECT_EQ(1, cbptr_->deleteSubnet6(ServerSelector::ALL(),
+                                       test_subnets_[2]->toText()));
+    subnets = cbptr_->getAllSubnets6(ServerSelector::ALL());
+    ASSERT_EQ(test_subnets_.size() - 3, subnets.size());
+
+    {
+        SCOPED_TRACE("DELETE second subnet audit entry");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::DELETE,
+                          "subnet deleted");
+    }
+
+    // Delete all.
+    EXPECT_EQ(1, cbptr_->deleteAllSubnets6(ServerSelector::ALL()));
+    subnets = cbptr_->getAllSubnets6(ServerSelector::ALL());
+    ASSERT_TRUE(subnets.empty());
+
+    {
+        SCOPED_TRACE("DELETE all subnets audit entry");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::DELETE,
+                          "deleted all subnets");
+    }
+}
+
+// Test that getAllSubnets6 throws appropriate exceptions for various
+// server selectors.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getAllSubnets6Selectors) {
+    // Supported selectors.
+    EXPECT_NO_THROW(cbptr_->getAllSubnets6(ServerSelector::UNASSIGNED()));
+    EXPECT_NO_THROW(cbptr_->getAllSubnets6(ServerSelector::ALL()));
+    EXPECT_NO_THROW(cbptr_->getAllSubnets6(ServerSelector::ONE("server1")));
+    EXPECT_NO_THROW(cbptr_->getAllSubnets6(ServerSelector::MULTIPLE({ "server1", "server2" })));
+
+    // Not supported selectors.
+    EXPECT_THROW(cbptr_->getAllSubnets6(ServerSelector::ANY()), isc::InvalidOperation);
+}
+
+// Test that subnets with different server associations are returned.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getAllSubnets6WithServerTags) {
+    auto subnet1 = test_subnets_[0];
+    auto subnet2 = test_subnets_[2];
+    auto subnet3 = test_subnets_[3];
+
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[0]));
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[2]));
+
+    EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ALL(),
+                                                subnet1));
+    EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ONE("server1"),
+                                                subnet2));
+    EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                                subnet3));
+
+    Subnet6Collection subnets;
+
+    // All three subnets are associated with the server1.
+    EXPECT_NO_THROW(subnets = cbptr_->getAllSubnets6(ServerSelector::ONE("server1")));
+    EXPECT_EQ(3, subnets.size());
+
+    // First subnet is associated with all servers.
+    auto returned_subnet = SubnetFetcher6::get(subnets, SubnetID(1024));
+    ASSERT_TRUE(returned_subnet);
+    EXPECT_TRUE(returned_subnet->hasAllServerTag());
+    EXPECT_FALSE(returned_subnet->hasServerTag(ServerTag("server1")));
+    EXPECT_FALSE(returned_subnet->hasServerTag(ServerTag("server2")));
+
+    // Second subnet is only associated with the server1.
+    returned_subnet = SubnetFetcher6::get(subnets, SubnetID(2048));
+    ASSERT_TRUE(returned_subnet);
+    EXPECT_FALSE(returned_subnet->hasAllServerTag());
+    EXPECT_TRUE(returned_subnet->hasServerTag(ServerTag("server1")));
+    EXPECT_FALSE(returned_subnet->hasServerTag(ServerTag("server2")));
+
+    // Third subnet is associated with both server1 and server2.
+    returned_subnet = SubnetFetcher6::get(subnets, SubnetID(4096));
+    ASSERT_TRUE(returned_subnet);
+    EXPECT_FALSE(returned_subnet->hasAllServerTag());
+    EXPECT_TRUE(returned_subnet->hasServerTag(ServerTag("server1")));
+    EXPECT_TRUE(returned_subnet->hasServerTag(ServerTag("server2")));
+
+    // For server2 we should only get two subnets, i.e. first and last.
+    EXPECT_NO_THROW(subnets = cbptr_->getAllSubnets6(ServerSelector::ONE("server2")));
+    EXPECT_EQ(2, subnets.size());
+
+    // First subnet is associated with all servers.
+    returned_subnet = SubnetFetcher6::get(subnets, SubnetID(1024));
+    ASSERT_TRUE(returned_subnet);
+    EXPECT_TRUE(returned_subnet->hasAllServerTag());
+    EXPECT_FALSE(returned_subnet->hasServerTag(ServerTag("server1")));
+    EXPECT_FALSE(returned_subnet->hasServerTag(ServerTag("server2")));
+
+    // Last subnet is associated with server1 and server2.
+    returned_subnet = SubnetFetcher6::get(subnets, SubnetID(4096));
+    ASSERT_TRUE(returned_subnet);
+    EXPECT_FALSE(returned_subnet->hasAllServerTag());
+    EXPECT_TRUE(returned_subnet->hasServerTag(ServerTag("server1")));
+    EXPECT_TRUE(returned_subnet->hasServerTag(ServerTag("server2")));
+
+    // Only the first subnet is associated with all servers.
+    EXPECT_NO_THROW(subnets = cbptr_->getAllSubnets6(ServerSelector::ALL()));
+    EXPECT_EQ(1, subnets.size());
+
+    returned_subnet = SubnetFetcher6::get(subnets, SubnetID(1024));
+    ASSERT_TRUE(returned_subnet);
+    EXPECT_TRUE(returned_subnet->hasAllServerTag());
+    EXPECT_FALSE(returned_subnet->hasServerTag(ServerTag("server1")));
+    EXPECT_FALSE(returned_subnet->hasServerTag(ServerTag("server2")));
+}
+
+// Test that selected subnet can be deleted.
+TEST_F(PgSqlConfigBackendDHCPv6Test, deleteSubnet6) {
+    // Create two servers in the database.
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[0]));
+    {
+        SCOPED_TRACE("CREATE audit entry for server");
+        testNewAuditEntry("dhcp6_server",
+                          AuditEntry::ModificationType::CREATE,
+                          "server set");
+    }
+
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[2]));
+    {
+        SCOPED_TRACE("CREATE audit entry for server");
+        testNewAuditEntry("dhcp6_server",
+                          AuditEntry::ModificationType::CREATE,
+                          "server set");
+    }
+
+    auto subnet1 = test_subnets_[0];
+    auto subnet2 = test_subnets_[2];
+    auto subnet3 = test_subnets_[3];
+
+    auto create_test_subnets = [&] () {
+        // Insert three subnets, one for all servers, one for server2 and one for two
+        // servers: server1 and server2.
+        EXPECT_NO_THROW(
+            cbptr_->createUpdateSubnet6(ServerSelector::ALL(), subnet1)
+        );
+        EXPECT_NO_THROW(
+            cbptr_->createUpdateSubnet6(ServerSelector::ONE("server2"), subnet2)
+        );
+        EXPECT_NO_THROW(
+            cbptr_->createUpdateSubnet6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                        subnet3)
+        );
+    };
+
+    create_test_subnets();
+
+    // Test that subnet is not deleted for a specified server selector.
+    auto test_no_delete = [this] (const std::string& test_case_name,
+                                  const ServerSelector& server_selector,
+                                  const Subnet6Ptr& subnet) {
+        SCOPED_TRACE(test_case_name);
+        uint64_t deleted_count = 0;
+        EXPECT_NO_THROW(
+            deleted_count = cbptr_->deleteSubnet6(server_selector, subnet->getID())
+        );
+        EXPECT_EQ(0, deleted_count);
+
+        deleted_count = 0;
+        EXPECT_NO_THROW(
+            deleted_count = cbptr_->deleteSubnet6(server_selector, subnet->toText())
+        );
+        EXPECT_EQ(0, deleted_count);
+    };
+
+    {
+        SCOPED_TRACE("Test valid but non matching server selectors");
+        test_no_delete("selector: one, actual: all", ServerSelector::ONE("server2"),
+                       subnet1);
+        test_no_delete("selector: all, actual: one", ServerSelector::ALL(),
+                       subnet2);
+        test_no_delete("selector: all, actual: multiple", ServerSelector::ALL(),
+                       subnet3);
+    }
+
+    // Test successful deletion of a subnet by ID.
+    auto test_delete_by_id = [this] (const std::string& test_case_name,
+                                     const ServerSelector& server_selector,
+                                     const Subnet6Ptr& subnet) {
+        SCOPED_TRACE(test_case_name);
+        uint64_t deleted_count = 0;
+        EXPECT_NO_THROW(
+            deleted_count = cbptr_->deleteSubnet6(server_selector, subnet->getID())
+        );
+        EXPECT_EQ(1, deleted_count);
+
+        EXPECT_FALSE(cbptr_->getSubnet6(server_selector, subnet->getID()));
+    };
+
+    test_delete_by_id("all servers", ServerSelector::ALL(), subnet1);
+    test_delete_by_id("any server", ServerSelector::ANY(), subnet2);
+    test_delete_by_id("one server", ServerSelector::ONE("server1"), subnet3);
+
+    // Re-create deleted subnets.
+    create_test_subnets();
+
+    // Test successful deletion of a subnet by prefix.
+    auto test_delete_by_prefix = [this] (const std::string& test_case_name,
+                                         const ServerSelector& server_selector,
+                                         const Subnet6Ptr& subnet) {
+        SCOPED_TRACE(test_case_name);
+        uint64_t deleted_count = 0;
+        EXPECT_NO_THROW(
+            deleted_count = cbptr_->deleteSubnet6(server_selector, subnet->toText())
+        );
+        EXPECT_EQ(1, deleted_count);
+
+        EXPECT_FALSE(cbptr_->getSubnet6(server_selector, subnet->toText()));
+    };
+
+    test_delete_by_prefix("all servers", ServerSelector::ALL(), subnet1);
+    test_delete_by_prefix("any server", ServerSelector::ANY(), subnet2);
+    test_delete_by_prefix("one server", ServerSelector::ONE("server1"), subnet3);
+}
+
+// Test that deleteSubnet6 by ID throws appropriate exceptions for various
+// server selectors.
+TEST_F(PgSqlConfigBackendDHCPv6Test, deleteSubnet6ByIdSelectors) {
+    // Supported selectors.
+    EXPECT_NO_THROW(cbptr_->deleteSubnet6(ServerSelector::ANY(), SubnetID(1)));
+    EXPECT_NO_THROW(cbptr_->deleteSubnet6(ServerSelector::ALL(), SubnetID(1)));
+    EXPECT_NO_THROW(cbptr_->deleteSubnet6(ServerSelector::ONE("server1"), SubnetID(1)));
+
+    // Not supported selectors.
+    EXPECT_THROW(cbptr_->deleteSubnet6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                           SubnetID(1)),
+                 isc::InvalidOperation);
+
+    // Not implemented selectors.
+    EXPECT_THROW(cbptr_->deleteSubnet6(ServerSelector::UNASSIGNED(), SubnetID(1)),
+                 isc::NotImplemented);
+}
+
+// Test that deleteSubnet6 by prefix throws appropriate exceptions for various
+// server selectors.
+TEST_F(PgSqlConfigBackendDHCPv6Test, deleteSubnet6ByPrefixSelectors) {
+    // Supported selectors.
+    EXPECT_NO_THROW(cbptr_->deleteSubnet6(ServerSelector::ANY(), "192.0.2.0/26"));
+    EXPECT_NO_THROW(cbptr_->deleteSubnet6(ServerSelector::ALL(), "192.0.2.0/26"));
+    EXPECT_NO_THROW(cbptr_->deleteSubnet6(ServerSelector::ONE("server1"), "192.0.2.0/26"));
+
+    // Not supported selectors.
+    EXPECT_THROW(cbptr_->deleteSubnet6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                           "192.0.2.0/26"),
+                 isc::InvalidOperation);
+
+    // Not implemented selectors.
+    EXPECT_THROW(cbptr_->deleteSubnet6(ServerSelector::UNASSIGNED(), "192.0.2.0/26"),
+                 isc::NotImplemented);
+}
+
+// Test that deleteAllSubnets6 throws appropriate exceptions for various
+// server selectors.
+TEST_F(PgSqlConfigBackendDHCPv6Test, deleteAllSubnets6Selectors) {
+    // Supported selectors.
+    EXPECT_NO_THROW(cbptr_->deleteAllSubnets6(ServerSelector::UNASSIGNED()));
+    EXPECT_NO_THROW(cbptr_->deleteAllSubnets6(ServerSelector::ALL()));
+    EXPECT_NO_THROW(cbptr_->deleteAllSubnets6(ServerSelector::ONE("server1")));
+
+    // Not supported selectors.
+    EXPECT_THROW(cbptr_->deleteAllSubnets6(ServerSelector::ANY()),
+                 isc::InvalidOperation);
+    EXPECT_THROW(cbptr_->deleteAllSubnets6(ServerSelector::MULTIPLE({ "server1", "server2" })),
+                 isc::InvalidOperation);
+}
+
+// Test that it is possible to retrieve and delete orphaned subnet.
+TEST_F(PgSqlConfigBackendDHCPv6Test, unassignedSubnet6) {
+    // Create the server.
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[0]));
+
+    // Create the subnets and associate them with the server1.
+    auto subnet = test_subnets_[0];
+    auto subnet2 = test_subnets_[2];
+    EXPECT_NO_THROW(
+        cbptr_->createUpdateSubnet6(ServerSelector::ONE("server1"), subnet)
+    );
+    EXPECT_NO_THROW(
+        cbptr_->createUpdateSubnet6(ServerSelector::ONE("server1"), subnet2)
+    );
+
+    // Delete the server. The subnets should be preserved but are considered orphaned,
+    // i.e. do not belong to any server.
+    uint64_t deleted_count = 0;
+    EXPECT_NO_THROW(deleted_count = cbptr_->deleteServer6(ServerTag("server1")));
+    EXPECT_EQ(1, deleted_count);
+
+    // Trying to fetch the subnet by server tag should return no result.
+    Subnet6Ptr returned_subnet;
+    EXPECT_NO_THROW(returned_subnet = cbptr_->getSubnet6(ServerSelector::ONE("server1"),
+                                                         subnet->getID()));
+    EXPECT_FALSE(returned_subnet);
+
+    // The same if we use other calls.
+    EXPECT_NO_THROW(returned_subnet = cbptr_->getSubnet6(ServerSelector::ONE("server1"),
+                                                         subnet->toText()));
+    EXPECT_FALSE(returned_subnet);
+
+    Subnet6Collection returned_subnets;
+    EXPECT_NO_THROW(returned_subnets = cbptr_->getAllSubnets6(ServerSelector::ONE("server1")));
+    EXPECT_TRUE(returned_subnets.empty());
+
+    EXPECT_NO_THROW(
+        returned_subnets = cbptr_->getModifiedSubnets6(ServerSelector::ONE("server1"),
+                                                       timestamps_["two days ago"])
+    );
+    EXPECT_TRUE(returned_subnets.empty());
+
+    // We should get the subnet if we ask for unassigned.
+    EXPECT_NO_THROW(returned_subnet = cbptr_->getSubnet6(ServerSelector::UNASSIGNED(),
+                                                         subnet->getID()));
+    ASSERT_TRUE(returned_subnet);
+
+    EXPECT_NO_THROW(returned_subnet = cbptr_->getSubnet6(ServerSelector::UNASSIGNED(),
+                                                         subnet->toText()));
+    ASSERT_TRUE(returned_subnet);
+
+    // Also if we ask for all unassigned subnets it should be returned.
+    EXPECT_NO_THROW(returned_subnets = cbptr_->getAllSubnets6(ServerSelector::UNASSIGNED()));
+    ASSERT_EQ(2, returned_subnets.size());
+
+    // Same for modified subnets.
+    EXPECT_NO_THROW(
+        returned_subnets = cbptr_->getModifiedSubnets6(ServerSelector::UNASSIGNED(),
+                                                       timestamps_["two days ago"])
+    );
+    ASSERT_EQ(2, returned_subnets.size());
+
+    // If we ask for any subnet by subnet id, it should be returned too.
+    EXPECT_NO_THROW(returned_subnet = cbptr_->getSubnet6(ServerSelector::ANY(),
+                                                         subnet->getID()));
+    ASSERT_TRUE(returned_subnet);
+
+    EXPECT_NO_THROW(returned_subnet = cbptr_->getSubnet6(ServerSelector::ANY(),
+                                                         subnet->toText()));
+    ASSERT_TRUE(returned_subnet);
+
+    // Deleting the subnet with the mismatched server tag should not affect our
+    // subnet.
+    EXPECT_NO_THROW(
+        deleted_count = cbptr_->deleteSubnet6(ServerSelector::ONE("server1"),
+                                              subnet->getID())
+    );
+    EXPECT_EQ(0, deleted_count);
+
+    // Also, if we delete all subnets for server1.
+    EXPECT_NO_THROW(
+        deleted_count = cbptr_->deleteAllSubnets6(ServerSelector::ONE("server1"))
+    );
+    EXPECT_EQ(0, deleted_count);
+
+    // We can delete this subnet when we specify ANY and the matching id.
+    EXPECT_NO_THROW(
+        deleted_count = cbptr_->deleteSubnet6(ServerSelector::ANY(), subnet->getID())
+    );
+    EXPECT_EQ(1, deleted_count);
+
+    // We can delete all subnets using UNASSIGNED selector.
+    EXPECT_NO_THROW(
+        deleted_count = cbptr_->deleteAllSubnets6(ServerSelector::UNASSIGNED());
+    );
+    EXPECT_EQ(1, deleted_count);
+}
+
+// Test that subnets modified after given time can be fetched.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getModifiedSubnets6) {
+    // Explicitly set timestamps of subnets. First subnet has a timestamp
+    // pointing to the future. Second subnet has timestamp pointing to the
+    // past (yesterday). Third subnet has a timestamp pointing to the
+    // past (an hour ago).
+    test_subnets_[1]->setModificationTime(timestamps_["tomorrow"]);
+    test_subnets_[2]->setModificationTime(timestamps_["yesterday"]);
+    test_subnets_[3]->setModificationTime(timestamps_["today"]);
+
+    // Insert subnets into the database.
+    for (int i = 1; i < test_subnets_.size(); ++i) {
+        cbptr_->createUpdateSubnet6(ServerSelector::ALL(),
+                                    test_subnets_[i]);
+    }
+
+    // Fetch subnets with timestamp later than today. Only one subnet
+    // should be returned.
+    Subnet6Collection
+        subnets = cbptr_->getModifiedSubnets6(ServerSelector::ALL(),
+                                              timestamps_["after today"]);
+    ASSERT_EQ(1, subnets.size());
+
+    // All subnets should also be returned for explicitly specified server tag.
+    subnets = cbptr_->getModifiedSubnets6(ServerSelector::ONE("server1"),
+                                          timestamps_["after today"]);
+    ASSERT_EQ(1, subnets.size());
+
+    // Fetch subnets with timestamp later than yesterday. We should get
+    // two subnets.
+    subnets = cbptr_->getModifiedSubnets6(ServerSelector::ALL(),
+                                          timestamps_["after yesterday"]);
+    ASSERT_EQ(2, subnets.size());
+
+    // Fetch subnets with timestamp later than tomorrow. Nothing should
+    // be returned.
+    subnets = cbptr_->getModifiedSubnets6(ServerSelector::ALL(),
+                                          timestamps_["after tomorrow"]);
+    ASSERT_TRUE(subnets.empty());
+}
+
+// Test that getModifiedSubnets6 throws appropriate exceptions for various
+// server selectors.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getModifiedSubnets6Selectors) {
+    // Supported selectors.
+    EXPECT_NO_THROW(cbptr_->getModifiedSubnets6(ServerSelector::UNASSIGNED(),
+                                                timestamps_["yesterday"]));
+    EXPECT_NO_THROW(cbptr_->getModifiedSubnets6(ServerSelector::ALL(),
+                                                timestamps_["yesterday"]));
+    EXPECT_NO_THROW(cbptr_->getModifiedSubnets6(ServerSelector::ONE("server1"),
+                                                timestamps_["yesterday"]));
+    EXPECT_NO_THROW(cbptr_->getModifiedSubnets6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                                timestamps_["yesterday"]));
+
+    // Not supported selectors.
+    EXPECT_THROW(cbptr_->getModifiedSubnets6(ServerSelector::ANY(),
+                                             timestamps_["yesterday"]),
+                 isc::InvalidOperation);
+}
+
+// Test that lifetimes in subnets are handled as expected.
+TEST_F(PgSqlConfigBackendDHCPv6Test, subnetLifetime) {
+    // Insert new subnet with unspecified valid lifetime
+    Triplet<uint32_t> unspecified;
+    Subnet6Ptr subnet(new Subnet6(IOAddress("2001:db8::"), 64, 30, 40,
+                                  unspecified, unspecified, 1111));
+    subnet->setIface("eth1");
+    cbptr_->createUpdateSubnet6(ServerSelector::ALL(), subnet);
+
+    // Fetch this subnet by subnet identifier
+    Subnet6Ptr returned_subnet = cbptr_->getSubnet6(ServerSelector::ALL(),
+                                                    subnet->getID());
+    ASSERT_TRUE(returned_subnet);
+
+    // Verified returned and original subnets match.
+    EXPECT_EQ(subnet->toElement()->str(), returned_subnet->toElement()->str());
+
+    // Update the preferred and valid lifetime.
+    subnet->setPreferred( Triplet<uint32_t>(100, 200, 300));
+    subnet->setValid( Triplet<uint32_t>(200, 300, 400));
+    cbptr_->createUpdateSubnet6(ServerSelector::ALL(), subnet);
+
+    // Fetch and verify again.
+    returned_subnet = cbptr_->getSubnet6(ServerSelector::ALL(), subnet->getID());
+    ASSERT_TRUE(returned_subnet);
+    EXPECT_EQ(subnet->toElement()->str(), returned_subnet->toElement()->str());
+}
+
+// Test that subnets belonging to a shared network can be retrieved.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getSharedNetworkSubnets6) {
+    // Assign test subnets to shared networks level1 and level2.
+    test_subnets_[1]->setSharedNetworkName("level1");
+    test_subnets_[2]->setSharedNetworkName("level2");
+    test_subnets_[3]->setSharedNetworkName("level2");
+
+    // Store shared networks in the database.
+    for (auto network : test_networks_) {
+        cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(), network);
+    }
+
+    // Store subnets in the database.
+    for (auto subnet : test_subnets_) {
+        cbptr_->createUpdateSubnet6(ServerSelector::ALL(), subnet);
+    }
+
+    // Fetch all subnets belonging to shared network level1.
+    Subnet6Collection subnets = cbptr_->getSharedNetworkSubnets6(ServerSelector::ALL(),
+                                                                 "level1");
+    ASSERT_EQ(1, subnets.size());
+
+    // Returned subnet should match test subnet #1.
+    EXPECT_TRUE(isEquivalent(test_subnets_[1]->toElement(),
+                             (*subnets.begin())->toElement()));
+
+    // All subnets should also be returned for ANY server.
+    subnets = cbptr_->getSharedNetworkSubnets6(ServerSelector::ANY(), "level1");
+    ASSERT_EQ(1, subnets.size());
+
+    // Returned subnet should match test subnet #1.
+    EXPECT_TRUE(isEquivalent(test_subnets_[1]->toElement(),
+                             (*subnets.begin())->toElement()));
+
+    // Fetch all subnets belonging to shared network level2.
+    subnets = cbptr_->getSharedNetworkSubnets6(ServerSelector::ALL(), "level2");
+    ASSERT_EQ(2, subnets.size());
+
+    ElementPtr test_list = Element::createList();
+    test_list->add(test_subnets_[2]->toElement());
+    test_list->add(test_subnets_[3]->toElement());
+
+    ElementPtr returned_list = Element::createList();
+    auto subnet = subnets.begin();
+    returned_list->add((*subnet)->toElement());
+    returned_list->add((*++subnet)->toElement());
+
+    EXPECT_TRUE(isEquivalent(returned_list, test_list));
+
+    // All subnets should also be returned for explicitly specified server tag.
+    subnets = cbptr_->getSharedNetworkSubnets6(ServerSelector::ONE("server1"), "level2");
+    ASSERT_EQ(2, subnets.size());
+
+    returned_list = Element::createList();
+    subnet = subnets.begin();
+    returned_list->add((*subnet)->toElement());
+    returned_list->add((*++subnet)->toElement());
+
+    EXPECT_TRUE(isEquivalent(returned_list, test_list));
+}
+
+// Test that pools are properly updated as a result a subnet update.
+TEST_F(PgSqlConfigBackendDHCPv6Test, subnetUpdatePools) {
+
+    auto test_subnet_update = [this](const std::string& subnet_prefix,
+                                     const SubnetID& subnet_id) {
+        // Add the subnet with two address pools and two prefix delegation
+        // pools.
+        EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ALL(),
+                                                    test_subnets_[0]));
+        // Make sure that the pools have been added to the database.
+        EXPECT_EQ(2, countRows("dhcp6_pool"));
+        EXPECT_EQ(2, countRows("dhcp6_pd_pool"));
+
+        // Create the subnet without options which updates the existing
+        // subnet.
+        Subnet6Ptr subnet(new Subnet6(IOAddress(subnet_prefix), 64, 30, 60, 50, 60,
+                                      subnet_id));
+        EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ALL(), subnet));
+        // Check that options are gone.
+        EXPECT_EQ(0, countRows("dhcp6_pool"));
+        EXPECT_EQ(0, countRows("dhcp6_pd_pool"));
+    };
+
+    {
+        SCOPED_TRACE("update subnet, modify subnet id");
+        // Create another subnet with the same prefix as the original subnet but
+        // different id. This is legal to update the subnet id if the prefix is
+        // stable. However, the new subnet has no address pools, so we need to
+        // check of the pools associated with the existing subnet instance are
+        // gone after the update.
+        test_subnet_update("2001:db8::", 2048);
+    }
+
+    {
+        SCOPED_TRACE("update subnet, modify prefix");
+        // Create a subnet with the same subnet id but different prefix.
+        // The prefix should be updated.
+        test_subnet_update("2001:db9::", 1024);
+    }
+}
+
+// Test that deleting a subnet triggers deletion of the options associated
+// with the subnet and pools.
+TEST_F(PgSqlConfigBackendDHCPv6Test, subnetOptions) {
+    // Add the subnet with two pools and three options.
+    EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ALL(), test_subnets_[0]));
+    EXPECT_EQ(2, countRows("dhcp6_pool"));
+    EXPECT_EQ(2, countRows("dhcp6_pd_pool"));
+    EXPECT_EQ(3, countRows("dhcp6_options"));
+
+    // The second subnet uses the same subnet id, so this operation should replace
+    // the existing subnet and its options. The new instance has four pools, each
+    // including one option, so we should end up with four options.
+    EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ALL(), test_subnets_[1]));
+    EXPECT_EQ(2, countRows("dhcp6_pool"));
+    EXPECT_EQ(2, countRows("dhcp6_pd_pool"));
+    EXPECT_EQ(4, countRows("dhcp6_options"));
+
+    // Add third subnet with a single option. The number of options in the database
+    // should now be 5.
+    EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ALL(), test_subnets_[2]));
+    EXPECT_EQ(2, countRows("dhcp6_pool"));
+    EXPECT_EQ(2, countRows("dhcp6_pd_pool"));
+    EXPECT_EQ(5, countRows("dhcp6_options"));
+
+    // Delete the subnet. All options and pools it contains should also be removed, leaving
+    // the last added subnet and its sole option.
+    EXPECT_NO_THROW(cbptr_->deleteSubnet6(ServerSelector::ALL(), test_subnets_[1]->getID()));
+    EXPECT_EQ(1, countRows("dhcp6_subnet"));
+    EXPECT_EQ(0, countRows("dhcp6_pool"));
+    EXPECT_EQ(0, countRows("dhcp6_pd_pool"));
+    EXPECT_EQ(1, countRows("dhcp6_options"));
+
+    // Add the first subnet again. We should now have 4 options: 3 options from the
+    // newly added subnet and one option from the existing subnet.
+    EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ALL(), test_subnets_[0]));
+    EXPECT_EQ(2, countRows("dhcp6_pool"));
+    EXPECT_EQ(2, countRows("dhcp6_pd_pool"));
+    EXPECT_EQ(4, countRows("dhcp6_options"));
+
+    // Delete the subnet including 3 options. The option from the other subnet should not
+    // be affected.
+    EXPECT_NO_THROW(cbptr_->deleteSubnet6(ServerSelector::ALL(), test_subnets_[0]->getID()));
+    EXPECT_EQ(1, countRows("dhcp6_subnet"));
+    EXPECT_EQ(0, countRows("dhcp6_pool"));
+    EXPECT_EQ(0, countRows("dhcp6_pd_pool"));
+    EXPECT_EQ(1, countRows("dhcp6_options"));
+}
+
+// Test that shared network can be inserted, fetched, updated and then
+// fetched again.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getSharedNetwork6) {
+    // Insert the server2 into the database.
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[2]));
+    {
+        SCOPED_TRACE("CREATE audit entry for server");
+        testNewAuditEntry("dhcp6_server",
+                          AuditEntry::ModificationType::CREATE,
+                          "server set");
+    }
+
+    auto shared_network = test_networks_[0];
+    auto shared_network2 = test_networks_[2];
+
+    // Insert two shared networks, one for all servers, and one for server2.
+    EXPECT_NO_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(),
+                                                       shared_network));
+    EXPECT_NO_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::ONE("server2"),
+                                                       shared_network2));
+
+    // We are not going to support selection of a single entry for multiple servers.
+    EXPECT_THROW(cbptr_->getSharedNetwork6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                           test_networks_[0]->getName()),
+                 isc::InvalidOperation);
+
+    // Test that this shared network will be fetched for various server selectors.
+    auto test_get_network = [this, &shared_network] (const std::string& test_case_name,
+                                                     const ServerSelector& server_selector,
+                                                     const std::string& expected_tag = ServerTag::ALL) {
+        SCOPED_TRACE(test_case_name);
+        SharedNetwork6Ptr network;
+        ASSERT_NO_THROW(network = cbptr_->getSharedNetwork6(server_selector,
+                                                            shared_network->getName()));
+        ASSERT_TRUE(network);
+
+        EXPECT_GT(network->getId(), 0);
+        ASSERT_EQ(1, network->getServerTags().size());
+        EXPECT_EQ(expected_tag, network->getServerTags().begin()->get());
+
+        // The easiest way to verify whether the returned shared network matches the
+        // inserted shared network is to convert both to text.
+        EXPECT_EQ(shared_network->toElement()->str(), network->toElement()->str());
+    };
+
+    {
+        SCOPED_TRACE("testing various server selectors before update");
+        test_get_network("all servers", ServerSelector::ALL());
+        test_get_network("one server", ServerSelector::ONE("server1"));
+        test_get_network("any server", ServerSelector::ANY());
+    }
+
+    {
+        SCOPED_TRACE("CREATE audit entry for a shared network");
+        testNewAuditEntry("dhcp6_shared_network",
+                          AuditEntry::ModificationType::CREATE,
+                          "shared network set");
+    }
+
+    // Update shared network in the database.
+    shared_network = test_networks_[1];
+    EXPECT_NO_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(),
+                                                       shared_network));
+
+    {
+        SCOPED_TRACE("testing various server selectors after update");
+        test_get_network("all servers after update", ServerSelector::ALL());
+        test_get_network("one server after update", ServerSelector::ONE("server1"));
+        test_get_network("any server after update", ServerSelector::ANY());
+    }
+
+    {
+        SCOPED_TRACE("UPDATE audit entry for a shared network");
+        testNewAuditEntry("dhcp6_shared_network",
+                          AuditEntry::ModificationType::UPDATE,
+                          "shared network set");
+    }
+
+    // The server2 specific shared network should not be returned if the
+    // server selector is not matching.
+    EXPECT_FALSE(cbptr_->getSharedNetwork6(ServerSelector::ALL(),
+                                           shared_network2->getName()));
+    EXPECT_FALSE(cbptr_->getSharedNetwork6(ServerSelector::ONE("server1"),
+                                           shared_network2->getName()));
+
+    {
+        SCOPED_TRACE("testing selectors for server2 specific shared network");
+        shared_network = shared_network2;
+        test_get_network("one server", ServerSelector::ONE("server2"), "server2");
+        test_get_network("any server", ServerSelector::ANY(), "server2");
+    }
+}
+
+// Test that getSharedNetwork6 throws appropriate exceptions for various
+// server selectors.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getSharedNetwork6Selectors) {
+    // Supported selectors.
+    EXPECT_NO_THROW(cbptr_->getSharedNetwork6(ServerSelector::ANY(), "level1"));
+    EXPECT_NO_THROW(cbptr_->getSharedNetwork6(ServerSelector::UNASSIGNED(), "level1"));
+    EXPECT_NO_THROW(cbptr_->getSharedNetwork6(ServerSelector::ALL(), "level1"));
+    EXPECT_NO_THROW(cbptr_->getSharedNetwork6(ServerSelector::ONE("server1"), "level1"));
+
+    // Not supported selectors.
+    EXPECT_THROW(cbptr_->getSharedNetwork6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                           "level1"),
+                 isc::InvalidOperation);
+}
+
+// Test that shared network may be created and updated and the server tags
+// are properly assigned to it.
+TEST_F(PgSqlConfigBackendDHCPv6Test, createUpdateSharedNetwork6) {
+    auto shared_network = test_networks_[0];
+
+    // An attempt to insert the shared network for non-existing server should fail.
+    EXPECT_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::ONE("server1"),
+                                                    shared_network),
+                 NullKeyError);
+
+    // Insert the server1 into the database.
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[0]));
+    {
+        SCOPED_TRACE("CREATE audit entry for server");
+        testNewAuditEntry("dhcp6_server",
+                          AuditEntry::ModificationType::CREATE,
+                          "server set");
+    }
+
+    // Insert the server2 into the database.
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[2]));
+    {
+        SCOPED_TRACE("CREATE audit entry for server");
+        testNewAuditEntry("dhcp6_server",
+                          AuditEntry::ModificationType::CREATE,
+                          "server set");
+    }
+
+    EXPECT_NO_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(),
+                                                       shared_network));
+    {
+        SCOPED_TRACE("CREATE audit entry for shared network and ALL servers");
+        testNewAuditEntry("dhcp6_shared_network",
+                          AuditEntry::ModificationType::CREATE,
+                          "shared network set");
+    }
+
+    EXPECT_NO_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                                       shared_network));
+    {
+        SCOPED_TRACE("UPDATE audit entry for shared network and MULTIPLE servers");
+        testNewAuditEntry("dhcp6_shared_network",
+                          AuditEntry::ModificationType::UPDATE,
+                          "shared network set");
+    }
+
+    SharedNetwork6Ptr network;
+    ASSERT_NO_THROW(network = cbptr_->getSharedNetwork6(ServerSelector::ANY(),
+                                                        shared_network->getName()));
+    ASSERT_TRUE(network);
+    EXPECT_TRUE(network->hasServerTag(ServerTag("server1")));
+    EXPECT_TRUE(network->hasServerTag(ServerTag("server2")));
+    EXPECT_FALSE(network->hasServerTag(ServerTag()));
+}
+
+// Test that createUpdateSharedNetwork6 throws appropriate exceptions for various
+// server selectors.
+TEST_F(PgSqlConfigBackendDHCPv6Test, createUpdateSharedNetwork6Selectors) {
+    ASSERT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[0]));
+    ASSERT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[2]));
+
+    // Supported selectors.
+    SharedNetwork6Ptr shared_network(new SharedNetwork6("all"));
+    EXPECT_NO_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(),
+                                                       shared_network));
+    shared_network.reset(new SharedNetwork6("one"));
+    EXPECT_NO_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::ONE("server1"),
+                                                       shared_network));
+    shared_network.reset(new SharedNetwork6("multiple"));
+    EXPECT_NO_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                                       shared_network));
+
+    // Not supported server selectors.
+    EXPECT_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::ANY(), shared_network),
+                 isc::InvalidOperation);
+
+    // Not implemented server selectors.
+    EXPECT_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::UNASSIGNED(),
+                                                    shared_network),
+                 isc::NotImplemented);
+}
+
+// Test that the information about unspecified optional parameters gets
+// propagated to the database.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getSharedNetwork6WithOptionalUnspecified) {
+    // Insert new shared network.
+    SharedNetwork6Ptr shared_network = test_networks_[2];
+    cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(), shared_network);
+
+    // Fetch this shared network by name.
+    SharedNetwork6Ptr
+        returned_network = cbptr_->getSharedNetwork6(ServerSelector::ALL(),
+                                                     test_networks_[2]->getName());
+    ASSERT_TRUE(returned_network);
+
+    EXPECT_TRUE(returned_network->getIface().unspecified());
+    EXPECT_TRUE(returned_network->getIface().empty());
+
+    EXPECT_TRUE(returned_network->getClientClass().unspecified());
+    EXPECT_TRUE(returned_network->getClientClass().empty());
+
+    EXPECT_TRUE(returned_network->getValid().unspecified());
+    EXPECT_EQ(0, returned_network->getValid().get());
+
+    EXPECT_TRUE(returned_network->getPreferred().unspecified());
+    EXPECT_EQ(0, returned_network->getPreferred().get());
+
+    EXPECT_TRUE(returned_network->getT1().unspecified());
+    EXPECT_EQ(0, returned_network->getT1().get());
+
+    EXPECT_TRUE(returned_network->getT2().unspecified());
+    EXPECT_EQ(0, returned_network->getT2().get());
+
+    EXPECT_TRUE(returned_network->getReservationsGlobal().unspecified());
+    EXPECT_FALSE(returned_network->getReservationsGlobal().get());
+
+    EXPECT_TRUE(returned_network->getReservationsInSubnet().unspecified());
+    EXPECT_TRUE(returned_network->getReservationsInSubnet().get());
+
+    EXPECT_TRUE(returned_network->getReservationsOutOfPool().unspecified());
+    EXPECT_FALSE(returned_network->getReservationsOutOfPool().get());
+
+    EXPECT_TRUE(returned_network->getCalculateTeeTimes().unspecified());
+    EXPECT_FALSE(returned_network->getCalculateTeeTimes().get());
+
+    EXPECT_TRUE(returned_network->getT1Percent().unspecified());
+    EXPECT_EQ(0.0, returned_network->getT1Percent().get());
+
+    EXPECT_TRUE(returned_network->getT2Percent().unspecified());
+    EXPECT_EQ(0.0, returned_network->getT2Percent().get());
+
+    EXPECT_TRUE(returned_network->getRapidCommit().unspecified());
+    EXPECT_FALSE(returned_network->getRapidCommit().get());
+
+    EXPECT_FALSE(returned_network->getDdnsSendUpdates().unspecified());
+    EXPECT_TRUE(returned_network->getDdnsSendUpdates().get());
+
+    EXPECT_FALSE(returned_network->getDdnsOverrideNoUpdate().unspecified());
+    EXPECT_TRUE(returned_network->getDdnsOverrideNoUpdate().get());
+
+    EXPECT_FALSE(returned_network->getDdnsOverrideClientUpdate().unspecified());
+    EXPECT_FALSE(returned_network->getDdnsOverrideClientUpdate().get());
+
+    EXPECT_FALSE(returned_network->getDdnsReplaceClientNameMode().unspecified());
+    EXPECT_EQ(D2ClientConfig::ReplaceClientNameMode::RCM_WHEN_PRESENT,
+              returned_network->getDdnsReplaceClientNameMode().get());
+
+    EXPECT_FALSE(returned_network->getDdnsGeneratedPrefix().unspecified());
+    EXPECT_EQ("myhost", returned_network->getDdnsGeneratedPrefix().get());
+
+    EXPECT_FALSE(returned_network->getDdnsQualifyingSuffix().unspecified());
+    EXPECT_EQ("example.org", returned_network->getDdnsQualifyingSuffix().get());
+}
+
+// Test that deleteSharedNetworkSubnets6 with not ANY selector throw.
+TEST_F(PgSqlConfigBackendDHCPv6Test, deleteSharedNetworkSubnets6) {
+    EXPECT_THROW(cbptr_->deleteSharedNetworkSubnets6(ServerSelector::UNASSIGNED(),
+                                                     test_networks_[1]->getName()),
+                 isc::InvalidOperation);
+    EXPECT_THROW(cbptr_->deleteSharedNetworkSubnets6(ServerSelector::ALL(),
+                                                     test_networks_[1]->getName()),
+                 isc::InvalidOperation);
+    EXPECT_THROW(cbptr_->deleteSharedNetworkSubnets6(ServerSelector::ONE("server1"),
+                                                     test_networks_[1]->getName()),
+                 isc::InvalidOperation);
+    EXPECT_THROW(cbptr_->deleteSharedNetworkSubnets6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                                     test_networks_[1]->getName()),
+                 isc::InvalidOperation);
+}
+
+// Test that all shared networks can be fetched.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getAllSharedNetworks6) {
+    // Insert test shared networks into the database. Note that the second shared
+    // network will overwrite the first shared network as they use the same name.
+    for (auto network : test_networks_) {
+        cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(), network);
+
+        // That shared network overrides the first one so the audit entry should
+        // indicate an update.
+        if ((network->getName() == "level1") && (!audit_entries_["all"].empty())) {
+            SCOPED_TRACE("UPDATE audit entry for the shared network " +
+                         network->getName());
+            testNewAuditEntry("dhcp6_shared_network",
+                              AuditEntry::ModificationType::UPDATE,
+                              "shared network set");
+
+        } else {
+            SCOPED_TRACE("CREATE audit entry for the shared network " +
+                         network->getName());
+            testNewAuditEntry("dhcp6_shared_network",
+                              AuditEntry::ModificationType::CREATE,
+                              "shared network set");
+        }
+    }
+
+    // Fetch all shared networks.
+    SharedNetwork6Collection networks =
+        cbptr_->getAllSharedNetworks6(ServerSelector::ALL());
+    ASSERT_EQ(test_networks_.size() - 1, networks.size());
+
+    // All shared networks should also be returned for explicitly specified
+    // server tag.
+    networks = cbptr_->getAllSharedNetworks6(ServerSelector::ONE("server1"));
+    ASSERT_EQ(test_networks_.size() - 1, networks.size());
+
+    // See if shared networks are returned ok.
+    for (auto i = 0; i < networks.size(); ++i) {
+        EXPECT_EQ(test_networks_[i + 1]->toElement()->str(),
+                  networks[i]->toElement()->str());
+        ASSERT_EQ(1, networks[i]->getServerTags().size());
+        EXPECT_EQ("all", networks[i]->getServerTags().begin()->get());
+    }
+
+    // Add some subnets.
+    test_networks_[1]->add(test_subnets_[0]);
+    test_subnets_[2]->setSharedNetworkName("level2");
+    test_networks_[2]->add(test_subnets_[3]);
+    cbptr_->createUpdateSubnet6(ServerSelector::ALL(), test_subnets_[0]);
+    cbptr_->createUpdateSubnet6(ServerSelector::ALL(), test_subnets_[2]);
+    cbptr_->createUpdateSubnet6(ServerSelector::ALL(), test_subnets_[3]);
+
+    // Both ways to attach a subnet are equivalent.
+    Subnet6Ptr subnet = cbptr_->getSubnet6(ServerSelector::ALL(),
+                                           test_subnets_[0]->getID());
+    ASSERT_TRUE(subnet);
+    EXPECT_EQ("level1", subnet->getSharedNetworkName());
+
+    {
+        SCOPED_TRACE("CREATE audit entry for subnets");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::CREATE,
+                          "subnet set", ServerSelector::ALL(), 3);
+    }
+
+    // Deleting non-existing shared network should return 0.
+    EXPECT_EQ(0, cbptr_->deleteSharedNetwork6(ServerSelector::ALL(),
+                                              "big-fish"));
+    // All shared networks should be still there.
+    ASSERT_EQ(test_networks_.size() - 1, networks.size());
+
+    // Should not delete the shared network for explicit server tag
+    // because our shared network is for all servers.
+    EXPECT_EQ(0, cbptr_->deleteSharedNetwork6(ServerSelector::ONE("server1"),
+                                              test_networks_[1]->getName()));
+
+    // Same for all shared networks.
+    EXPECT_EQ(0, cbptr_->deleteAllSharedNetworks6(ServerSelector::ONE("server1")));
+
+    // Delete first shared network with it subnets and verify it is gone.
+    // Begin by its subnet.
+    EXPECT_EQ(1, cbptr_->deleteSharedNetworkSubnets6(ServerSelector::ANY(),
+                                                     test_networks_[1]->getName()));
+
+    {
+        SCOPED_TRACE("DELETE audit entry for subnets of the first shared network");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::DELETE,
+                          "deleted all subnets for a shared network");
+    }
+
+    // Check that the subnet is gone..
+    subnet = cbptr_->getSubnet6(ServerSelector::ALL(),
+                                test_subnets_[0]->getID());
+    EXPECT_FALSE(subnet);
+
+    // And after the shared network itself.
+    EXPECT_EQ(1, cbptr_->deleteSharedNetwork6(ServerSelector::ALL(),
+                                              test_networks_[1]->getName()));
+    networks = cbptr_->getAllSharedNetworks6(ServerSelector::ALL());
+    ASSERT_EQ(test_networks_.size() - 2, networks.size());
+
+    {
+        SCOPED_TRACE("DELETE audit entry for the first shared network");
+        testNewAuditEntry("dhcp6_shared_network",
+                          AuditEntry::ModificationType::DELETE,
+                          "shared network deleted");
+    }
+
+    // Delete all.
+    EXPECT_EQ(2, cbptr_->deleteAllSharedNetworks6(ServerSelector::ALL()));
+    networks = cbptr_->getAllSharedNetworks6(ServerSelector::ALL());
+    ASSERT_TRUE(networks.empty());
+
+    {
+        SCOPED_TRACE("DELETE audit entry for the remaining two shared networks");
+        // The last parameter indicates that we expect two new audit entries.
+        testNewAuditEntry("dhcp6_shared_network",
+                          AuditEntry::ModificationType::DELETE,
+                          "deleted all shared networks",
+                          ServerSelector::ALL(), 2);
+    }
+
+    // Check that subnets are still there but detached.
+    subnet = cbptr_->getSubnet6(ServerSelector::ALL(),
+                                test_subnets_[2]->getID());
+    ASSERT_TRUE(subnet);
+    EXPECT_TRUE(subnet->getSharedNetworkName().empty());
+    subnet = cbptr_->getSubnet6(ServerSelector::ALL(),
+                                test_subnets_[3]->getID());
+    ASSERT_TRUE(subnet);
+    EXPECT_TRUE(subnet->getSharedNetworkName().empty());
+}
+
+// Test that getAllSharedNetworks6 throws appropriate exceptions for various
+// server selectors.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getAllSharedNetworks6Selectors) {
+    // Supported selectors.
+    EXPECT_NO_THROW(cbptr_->getAllSharedNetworks6(ServerSelector::UNASSIGNED()));
+    EXPECT_NO_THROW(cbptr_->getAllSharedNetworks6(ServerSelector::ALL()));
+    EXPECT_NO_THROW(cbptr_->getAllSharedNetworks6(ServerSelector::ONE("server1")));
+    EXPECT_NO_THROW(cbptr_->getAllSharedNetworks6(ServerSelector::MULTIPLE({ "server1", "server2" })));
+
+    // Not supported selectors.
+    EXPECT_THROW(cbptr_->getAllSharedNetworks6(ServerSelector::ANY()),
+                 isc::InvalidOperation);
+}
+
+// Test that shared networks with different server associations are returned.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getAllSharedNetworks6WithServerTags) {
+    auto shared_network1 = test_networks_[0];
+    auto shared_network2 = test_networks_[2];
+    auto shared_network3 = test_networks_[3];
+
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[0]));
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[2]));
+
+    EXPECT_NO_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(),
+                                                       shared_network1));
+    EXPECT_NO_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::ONE("server1"),
+                                                       shared_network2));
+    EXPECT_NO_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                                       shared_network3));
+
+    SharedNetwork6Collection networks;
+
+    // All three networks are associated with the server1.
+    EXPECT_NO_THROW(networks = cbptr_->getAllSharedNetworks6(ServerSelector::ONE("server1")));
+    EXPECT_EQ(3, networks.size());
+
+    // First network is associated with all servers.
+    auto returned_network = SharedNetworkFetcher6::get(networks, "level1");
+    ASSERT_TRUE(returned_network);
+    EXPECT_TRUE(returned_network->hasAllServerTag());
+    EXPECT_FALSE(returned_network->hasServerTag(ServerTag("server1")));
+    EXPECT_FALSE(returned_network->hasServerTag(ServerTag("server2")));
+
+    // Second network is only associated with the server1.
+    returned_network = SharedNetworkFetcher6::get(networks, "level2");
+    ASSERT_TRUE(returned_network);
+    EXPECT_FALSE(returned_network->hasAllServerTag());
+    EXPECT_TRUE(returned_network->hasServerTag(ServerTag("server1")));
+    EXPECT_FALSE(returned_network->hasServerTag(ServerTag("server2")));
+
+    // Third network is associated with both server1 and server2.
+    returned_network = SharedNetworkFetcher6::get(networks, "level3");
+    ASSERT_TRUE(returned_network);
+    EXPECT_FALSE(returned_network->hasAllServerTag());
+    EXPECT_TRUE(returned_network->hasServerTag(ServerTag("server1")));
+    EXPECT_TRUE(returned_network->hasServerTag(ServerTag("server2")));
+
+    // For server2 we should only get two shared networks, i.e. first and last.
+    EXPECT_NO_THROW(networks = cbptr_->getAllSharedNetworks6(ServerSelector::ONE("server2")));
+    EXPECT_EQ(2, networks.size());
+
+    // First shared network is associated with all servers.
+    returned_network = SharedNetworkFetcher6::get(networks, "level1");
+    ASSERT_TRUE(returned_network);
+    EXPECT_TRUE(returned_network->hasAllServerTag());
+    EXPECT_FALSE(returned_network->hasServerTag(ServerTag("server1")));
+    EXPECT_FALSE(returned_network->hasServerTag(ServerTag("server2")));
+
+    // Last shared network is associated with server1 and server2.
+    returned_network = SharedNetworkFetcher6::get(networks, "level3");
+    ASSERT_TRUE(returned_network);
+    EXPECT_FALSE(returned_network->hasAllServerTag());
+    EXPECT_TRUE(returned_network->hasServerTag(ServerTag("server1")));
+    EXPECT_TRUE(returned_network->hasServerTag(ServerTag("server2")));
+
+    // Only the first shared network is associated with all servers.
+    EXPECT_NO_THROW(networks = cbptr_->getAllSharedNetworks6(ServerSelector::ALL()));
+    EXPECT_EQ(1, networks.size());
+
+    returned_network = SharedNetworkFetcher6::get(networks, "level1");
+    ASSERT_TRUE(returned_network);
+    EXPECT_TRUE(returned_network->hasAllServerTag());
+    EXPECT_FALSE(returned_network->hasServerTag(ServerTag("server1")));
+    EXPECT_FALSE(returned_network->hasServerTag(ServerTag("server2")));
+}
+
+// Test that shared networks modified after given time can be fetched.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getModifiedSharedNetworks6) {
+    // Explicitly set timestamps of shared networks. First shared
+    // network has a timestamp pointing to the future. Second shared
+    // network has timestamp pointing to the past (yesterday).
+    // Third shared network has a timestamp pointing to the
+    // past (an hour ago).
+    test_networks_[1]->setModificationTime(timestamps_["tomorrow"]);
+    test_networks_[2]->setModificationTime(timestamps_["yesterday"]);
+    test_networks_[3]->setModificationTime(timestamps_["today"]);
+
+    // Insert shared networks into the database.
+    for (int i = 1; i < test_networks_.size(); ++i) {
+        cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(),
+                                           test_networks_[i]);
+    }
+
+    // Fetch shared networks with timestamp later than today. Only one
+    // shared network  should be returned.
+    SharedNetwork6Collection
+        networks = cbptr_->getModifiedSharedNetworks6(ServerSelector::ALL(),
+                                                      timestamps_["after today"]);
+    ASSERT_EQ(1, networks.size());
+
+    // Fetch shared networks with timestamp later than yesterday. We
+    // should get two shared networks.
+    networks = cbptr_->getModifiedSharedNetworks6(ServerSelector::ALL(),
+                                                 timestamps_["after yesterday"]);
+    ASSERT_EQ(2, networks.size());
+
+    // Fetch shared networks with timestamp later than tomorrow. Nothing
+    // should be returned.
+    networks = cbptr_->getModifiedSharedNetworks6(ServerSelector::ALL(),
+                                                  timestamps_["after tomorrow"]);
+    ASSERT_TRUE(networks.empty());
+}
+
+// Test that getModifiedSharedNetworks6 throws appropriate exceptions for various
+// server selectors.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getModifiedSharedNetworks6Selectors) {
+    // Supported selectors.
+    EXPECT_NO_THROW(cbptr_->getModifiedSharedNetworks6(ServerSelector::UNASSIGNED(),
+                                                       timestamps_["yesterday"]));
+    EXPECT_NO_THROW(cbptr_->getModifiedSharedNetworks6(ServerSelector::ALL(),
+                                                       timestamps_["yesterday"]));
+    EXPECT_NO_THROW(cbptr_->getModifiedSharedNetworks6(ServerSelector::ONE("server1"),
+                                                       timestamps_["yesterday"]));
+    EXPECT_NO_THROW(cbptr_->getModifiedSharedNetworks6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                                       timestamps_["yesterday"]));
+
+    // Not supported selectors.
+    EXPECT_THROW(cbptr_->getModifiedSharedNetworks6(ServerSelector::ANY(),
+                                                    timestamps_["yesterday"]),
+                 isc::InvalidOperation);
+}
+
+// Test that selected shared network can be deleted.
+TEST_F(PgSqlConfigBackendDHCPv6Test, deleteSharedNetwork6) {
+    // Create two servers in the database.
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[0]));
+    {
+        SCOPED_TRACE("CREATE audit entry for server");
+        testNewAuditEntry("dhcp6_server",
+                          AuditEntry::ModificationType::CREATE,
+                          "server set");
+    }
+
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[2]));
+    {
+        SCOPED_TRACE("CREATE audit entry for server");
+        testNewAuditEntry("dhcp6_server",
+                          AuditEntry::ModificationType::CREATE,
+                          "server set");
+    }
+
+    auto shared_network1 = test_networks_[0];
+    auto shared_network2 = test_networks_[2];
+    auto shared_network3 = test_networks_[3];
+
+    // Insert two shared networks, one for all servers, and one for server2.
+    EXPECT_NO_THROW(
+        cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(), shared_network1)
+    );
+    EXPECT_NO_THROW(
+        cbptr_->createUpdateSharedNetwork6(ServerSelector::ONE("server2"), shared_network2)
+    );
+    EXPECT_NO_THROW(
+        cbptr_->createUpdateSharedNetwork6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                           shared_network3)
+    );
+
+    auto test_no_delete = [this] (const std::string& test_case_name,
+                                  const ServerSelector& server_selector,
+                                  const SharedNetwork6Ptr& shared_network) {
+        SCOPED_TRACE(test_case_name);
+        uint64_t deleted_count = 0;
+        EXPECT_NO_THROW(
+            deleted_count = cbptr_->deleteSharedNetwork6(server_selector,
+                                                         shared_network->getName())
+        );
+        EXPECT_EQ(0, deleted_count);
+    };
+
+    {
+        SCOPED_TRACE("Test valid but non matching server selectors");
+        test_no_delete("selector: one, actual: all", ServerSelector::ONE("server2"),
+                       shared_network1);
+        test_no_delete("selector: all, actual: one", ServerSelector::ALL(),
+                       shared_network2);
+        test_no_delete("selector: all, actual: multiple", ServerSelector::ALL(),
+                       shared_network3);
+    }
+
+    // We are not going to support deletion of a single entry for multiple servers.
+    EXPECT_THROW(cbptr_->deleteSharedNetwork6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                              shared_network3->getName()),
+                 isc::InvalidOperation);
+
+    // We currently don't support deleting a shared network with specifying
+    // an unassigned server tag. Use ANY to delete any subnet instead.
+    EXPECT_THROW(cbptr_->deleteSharedNetwork6(ServerSelector::UNASSIGNED(),
+                                              shared_network1->getName()),
+                 isc::NotImplemented);
+
+    // Test successful deletion of a shared network.
+    auto test_delete = [this] (const std::string& test_case_name,
+                               const ServerSelector& server_selector,
+                               const SharedNetwork6Ptr& shared_network) {
+        SCOPED_TRACE(test_case_name);
+        uint64_t deleted_count = 0;
+        EXPECT_NO_THROW(
+            deleted_count = cbptr_->deleteSharedNetwork6(server_selector,
+                                                         shared_network->getName())
+        );
+        EXPECT_EQ(1, deleted_count);
+
+        EXPECT_FALSE(cbptr_->getSharedNetwork6(server_selector,
+                                               shared_network->getName()));
+    };
+
+    test_delete("all servers", ServerSelector::ALL(), shared_network1);
+    test_delete("any server", ServerSelector::ANY(), shared_network2);
+    test_delete("one server", ServerSelector::ONE("server1"), shared_network3);
+}
+
+// Test that deleteSharedNetwork6 throws appropriate exceptions for various
+// server selectors.
+TEST_F(PgSqlConfigBackendDHCPv6Test, deleteSharedNetwork6Selectors) {
+    // Supported selectors.
+    EXPECT_NO_THROW(cbptr_->deleteSharedNetwork6(ServerSelector::ANY(), "level1"));
+    EXPECT_NO_THROW(cbptr_->deleteSharedNetwork6(ServerSelector::ALL(), "level1"));
+    EXPECT_NO_THROW(cbptr_->deleteSharedNetwork6(ServerSelector::ONE("server1"), "level1"));
+
+    // Not supported selectors.
+    EXPECT_THROW(cbptr_->deleteSharedNetwork6(ServerSelector::MULTIPLE({ "server1", "server2" }),
+                                           "level1"),
+                 isc::InvalidOperation);
+
+    // Not implemented selectors.
+    EXPECT_THROW(cbptr_->deleteSharedNetwork6(ServerSelector::UNASSIGNED(), "level1"),
+                 isc::NotImplemented);
+}
+
+// Test that deleteAllSharedNetworks6 throws appropriate exceptions for various
+// server selectors.
+TEST_F(PgSqlConfigBackendDHCPv6Test, deleteAllSharedNetworks6Selectors) {
+    // Supported selectors.
+    EXPECT_NO_THROW(cbptr_->deleteAllSharedNetworks6(ServerSelector::UNASSIGNED()));
+    EXPECT_NO_THROW(cbptr_->deleteAllSharedNetworks6(ServerSelector::ALL()));
+    EXPECT_NO_THROW(cbptr_->deleteAllSharedNetworks6(ServerSelector::ONE("server1")));
+
+    // Not supported selectors.
+    EXPECT_THROW(cbptr_->deleteAllSharedNetworks6(ServerSelector::ANY()),
+                 isc::InvalidOperation);
+    EXPECT_THROW(cbptr_->deleteAllSharedNetworks6(ServerSelector::MULTIPLE({ "server1", "server2" })),
+                 isc::InvalidOperation);
+}
+
+// Test that it is possible to retrieve and delete orphaned shared network.
+TEST_F(PgSqlConfigBackendDHCPv6Test, unassignedSharedNetwork) {
+    // Create the server.
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[0]));
+
+    // Create the shared networks and associate them with the server1.
+    auto shared_network = test_networks_[0];
+    auto shared_network2 = test_networks_[2];
+    EXPECT_NO_THROW(
+        cbptr_->createUpdateSharedNetwork6(ServerSelector::ONE("server1"), shared_network)
+    );
+    EXPECT_NO_THROW(
+        cbptr_->createUpdateSharedNetwork6(ServerSelector::ONE("server1"), shared_network2)
+    );
+
+    // Delete the server. The shared networks should be preserved but are
+    // considered orphaned, i.e. do not belong to any server.
+    uint64_t deleted_count = 0;
+    EXPECT_NO_THROW(deleted_count = cbptr_->deleteServer6(ServerTag("server1")));
+    EXPECT_EQ(1, deleted_count);
+
+    // Trying to fetch this shared network by server tag should return no result.
+    SharedNetwork6Ptr returned_network;
+    EXPECT_NO_THROW(returned_network = cbptr_->getSharedNetwork6(ServerSelector::ONE("server1"),
+                                                                 "level1"));
+    EXPECT_FALSE(returned_network);
+
+    // The same if we use other calls.
+    SharedNetwork6Collection returned_networks;
+    EXPECT_NO_THROW(
+        returned_networks = cbptr_->getAllSharedNetworks6(ServerSelector::ONE("server1"))
+    );
+    EXPECT_TRUE(returned_networks.empty());
+
+    EXPECT_NO_THROW(
+        returned_networks = cbptr_->getModifiedSharedNetworks6(ServerSelector::ONE("server1"),
+                                                               timestamps_["two days ago"])
+    );
+    EXPECT_TRUE(returned_networks.empty());
+
+    // We should get the shared network if we ask for unassigned.
+    EXPECT_NO_THROW(returned_network = cbptr_->getSharedNetwork6(ServerSelector::UNASSIGNED(),
+                                                                 "level1"));
+    ASSERT_TRUE(returned_network);
+
+    // Also if we ask for all unassigned networks it should be returned.
+    EXPECT_NO_THROW(returned_networks = cbptr_->getAllSharedNetworks6(ServerSelector::UNASSIGNED()));
+    ASSERT_EQ(2, returned_networks.size());
+
+    // And all modified.
+    EXPECT_NO_THROW(
+        returned_networks = cbptr_->getModifiedSharedNetworks6(ServerSelector::UNASSIGNED(),
+                                                               timestamps_["two days ago"])
+    );
+    ASSERT_EQ(2, returned_networks.size());
+
+    // If we ask for any network by name, it should be returned too.
+    EXPECT_NO_THROW(returned_network = cbptr_->getSharedNetwork6(ServerSelector::ANY(),
+                                                                 "level1"));
+    ASSERT_TRUE(returned_network);
+
+    // Deleting a shared network with the mismatched server tag should not affect
+    // our shared network.
+    EXPECT_NO_THROW(
+        deleted_count = cbptr_->deleteSharedNetwork6(ServerSelector::ONE("server1"),
+                                                     "level1")
+    );
+    EXPECT_EQ(0, deleted_count);
+
+    // Also, if we delete all shared networks for server1.
+    EXPECT_NO_THROW(
+        deleted_count = cbptr_->deleteAllSharedNetworks6(ServerSelector::ONE("server1"))
+    );
+    EXPECT_EQ(0, deleted_count);
+
+    // We can delete this shared network when we specify ANY and the matching name.
+    EXPECT_NO_THROW(
+        deleted_count = cbptr_->deleteSharedNetwork6(ServerSelector::ANY(), "level1")
+    );
+    EXPECT_EQ(1, deleted_count);
+
+    // We can delete all second networks using UNASSIGNED selector.
+    EXPECT_NO_THROW(
+        deleted_count = cbptr_->deleteAllSharedNetworks6(ServerSelector::UNASSIGNED());
+    );
+    EXPECT_EQ(1, deleted_count);
+}
+
+// Test that lifetimes in shared networks are handled as expected.
+TEST_F(PgSqlConfigBackendDHCPv6Test, sharedNetworkLifetime) {
+    // Insert new shared network with unspecified valid lifetime
+    SharedNetwork6Ptr network(new SharedNetwork6("foo"));
+    Triplet<uint32_t> unspecified;
+    network->setPreferred(unspecified);
+    network->setValid(unspecified);
+    network->setIface("eth1");
+    cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(), network);
+
+    // Fetch this shared network.
+    SharedNetwork6Ptr returned_network =
+        cbptr_->getSharedNetwork6(ServerSelector::ALL(), "foo");
+    ASSERT_TRUE(returned_network);
+
+    // Verified returned and original shared networks match.
+    EXPECT_EQ(network->toElement()->str(),
+              returned_network->toElement()->str());
+
+    // Update the preferred and valid lifetime.
+    network->setPreferred( Triplet<uint32_t>(100, 200, 300));
+    network->setValid( Triplet<uint32_t>(200, 300, 400));
+    cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(), network);
+
+    // Fetch and verify again.
+    returned_network = cbptr_->getSharedNetwork6(ServerSelector::ALL(), "foo");
+    ASSERT_TRUE(returned_network);
+    EXPECT_EQ(network->toElement()->str(),
+              returned_network->toElement()->str());
+}
+
+// Test that deleting a shared network triggers deletion of the options
+// associated with the shared network.
+TEST_F(PgSqlConfigBackendDHCPv6Test, sharedNetworkOptions) {
+    // Add shared network with three options.
+    EXPECT_NO_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(), test_networks_[0]));
+    EXPECT_EQ(3, countRows("dhcp6_options"));
+
+    // Add another shared network with a single option. The numnber of options in the
+    // database should now be 4.
+    EXPECT_NO_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(), test_networks_[2]));
+    EXPECT_EQ(4, countRows("dhcp6_options"));
+
+    // The second shared network uses the same name as the first shared network, so
+    // this operation should replace the existing shared network and its options.
+    EXPECT_NO_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(), test_networks_[1]));
+    EXPECT_EQ(1, countRows("dhcp6_options"));
+
+    // Remove the shared network. This should not affect options assigned to the
+    // other shared network.
+    EXPECT_NO_THROW(cbptr_->deleteSharedNetwork6(ServerSelector::ALL(),
+                                                 test_networks_[1]->getName()));
+    EXPECT_EQ(1, countRows("dhcp6_shared_network"));
+    EXPECT_EQ(1, countRows("dhcp6_options"));
+
+    // Create the first option again. The number of options should be equal to the
+    // sum of options associated with both shared networks.
+    EXPECT_NO_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(), test_networks_[0]));
+    EXPECT_EQ(4, countRows("dhcp6_options"));
+
+    // Delete this shared network. This should not affect the option associated
+    // with the remaining shared network.
+    EXPECT_NO_THROW(cbptr_->deleteSharedNetwork6(ServerSelector::ALL(),
+                                                 test_networks_[0]->getName()));
+    EXPECT_EQ(1, countRows("dhcp6_shared_network"));
+    EXPECT_EQ(1, countRows("dhcp6_options"));
+}
+
+// Test that option definition can be inserted, fetched, updated and then
+// fetched again.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getOptionDef6) {
+    // Insert new option definition.
+    OptionDefinitionPtr option_def = test_option_defs_[0];
+    cbptr_->createUpdateOptionDef6(ServerSelector::ALL(), option_def);
+
+    // Fetch this option_definition by subnet identifier.
+    OptionDefinitionPtr returned_option_def =
+        cbptr_->getOptionDef6(ServerSelector::ALL(),
+                              test_option_defs_[0]->getCode(),
+                              test_option_defs_[0]->getOptionSpaceName());
+    ASSERT_TRUE(returned_option_def);
+    EXPECT_GT(returned_option_def->getId(), 0);
+    ASSERT_EQ(1, returned_option_def->getServerTags().size());
+    EXPECT_EQ("all", returned_option_def->getServerTags().begin()->get());
+
+    EXPECT_TRUE(returned_option_def->equals(*option_def));
+
+    {
+        SCOPED_TRACE("CREATE audit entry for an option definition");
+        testNewAuditEntry("dhcp6_option_def",
+                          AuditEntry::ModificationType::CREATE,
+                          "option definition set");
+    }
+
+    // Update the option definition in the database.
+    OptionDefinitionPtr option_def2 = test_option_defs_[1];
+    cbptr_->createUpdateOptionDef6(ServerSelector::ALL(), option_def2);
+
+    // Fetch updated option definition and see if it matches.
+    returned_option_def = cbptr_->getOptionDef6(ServerSelector::ALL(),
+                                                test_option_defs_[1]->getCode(),
+                                                test_option_defs_[1]->getOptionSpaceName());
+    EXPECT_TRUE(returned_option_def->equals(*option_def2));
+
+    // Fetching option definition for an explicitly specified server tag
+    // should succeed too.
+    returned_option_def = cbptr_->getOptionDef6(ServerSelector::ONE("server1"),
+                                                test_option_defs_[1]->getCode(),
+                                                test_option_defs_[1]->getOptionSpaceName());
+    EXPECT_TRUE(returned_option_def->equals(*option_def2));
+
+    {
+        SCOPED_TRACE("UPDATE audit entry for an option definition");
+        testNewAuditEntry("dhcp6_option_def",
+                          AuditEntry::ModificationType::UPDATE,
+                          "option definition set");
+    }
+}
+
+// This test verifies that it is possible to differentiate between the
+// option definitions by server tag and that the option definition
+// specified for the particular server overrides the definition for
+// all servers.
+TEST_F(PgSqlConfigBackendDHCPv6Test, optionDefs6WithServerTags) {
+    OptionDefinitionPtr option1 = test_option_defs_[0];
+    OptionDefinitionPtr option2 = test_option_defs_[1];
+    OptionDefinitionPtr option3 = test_option_defs_[4];
+
+    // An attempt to create option definition for non-existing server should
+    // fail.
+    EXPECT_THROW(cbptr_->createUpdateOptionDef6(ServerSelector::ONE("server1"),
+                                                option1),
+                 NullKeyError);
+
+    // Create two servers.
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[1]));
+    {
+        SCOPED_TRACE("server1 is created");
+        testNewAuditEntry("dhcp6_server",
+                          AuditEntry::ModificationType::CREATE,
+                          "server set");
+    }
+
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[2]));
+    {
+        SCOPED_TRACE("server2 is created");
+        testNewAuditEntry("dhcp6_server",
+                          AuditEntry::ModificationType::CREATE,
+                          "server set");
+    }
+
+    // This time creation of the option definition for the server1 should pass.
+    EXPECT_NO_THROW(cbptr_->createUpdateOptionDef6(ServerSelector::ONE("server1"),
+                                                   option1));
+    {
+        SCOPED_TRACE("option definition for server1 is set");
+        // The value of 3 means there should be 3 audit entries available for the
+        // server1, two that indicate creation of the servers and one that we
+        // validate, which sets the option definition.
+        testNewAuditEntry("dhcp6_option_def",
+                          AuditEntry::ModificationType::CREATE,
+                          "option definition set",
+                          ServerSelector::ONE("server1"),
+                          3, 1);
+    }
+
+    // Creation of the option definition for the server2 should also pass.
+    EXPECT_NO_THROW(cbptr_->createUpdateOptionDef6(ServerSelector::ONE("server2"),
+                                                   option2));
+    {
+        SCOPED_TRACE("option definition for server2 is set");
+        // Same as in case of the server1, there should be 3 audit entries and
+        // we validate one of them.
+        testNewAuditEntry("dhcp6_option_def",
+                          AuditEntry::ModificationType::CREATE,
+                          "option definition set",
+                          ServerSelector::ONE("server2"),
+                          3, 1);
+    }
+
+    // Finally, creation of the option definition for all servers should
+    // also pass.
+    EXPECT_NO_THROW(cbptr_->createUpdateOptionDef6(ServerSelector::ALL(),
+                                                   option3));
+    {
+        SCOPED_TRACE("option definition for server2 is set");
+        // There should be one new audit entry for all servers. It logs
+        // the insertion of the option definition.
+        testNewAuditEntry("dhcp6_option_def",
+                          AuditEntry::ModificationType::CREATE,
+                          "option definition set",
+                          ServerSelector::ALL(),
+                          1, 1);
+    }
+
+    OptionDefinitionPtr returned_option_def;
+
+    // Try to fetch the option definition specified for all servers. It should
+    // return the third one.
+    EXPECT_NO_THROW(
+        returned_option_def = cbptr_->getOptionDef6(ServerSelector::ALL(),
+                                                    option3->getCode(),
+                                                    option3->getOptionSpaceName())
+    );
+    ASSERT_TRUE(returned_option_def);
+    EXPECT_TRUE(returned_option_def->equals(*option3));
+
+    // Try to fetch the option definition specified for server1. It should
+    // override the definition for all servers.
+    EXPECT_NO_THROW(
+        returned_option_def = cbptr_->getOptionDef6(ServerSelector::ONE("server1"),
+                                                    option1->getCode(),
+                                                    option1->getOptionSpaceName())
+    );
+    ASSERT_TRUE(returned_option_def);
+    EXPECT_TRUE(returned_option_def->equals(*option1));
+
+    // The same in case of the server2.
+    EXPECT_NO_THROW(
+        returned_option_def = cbptr_->getOptionDef6(ServerSelector::ONE("server2"),
+                                                    option2->getCode(),
+                                                    option2->getOptionSpaceName())
+    );
+    ASSERT_TRUE(returned_option_def);
+    EXPECT_TRUE(returned_option_def->equals(*option2));
+
+    OptionDefContainer returned_option_defs;
+
+    // Try to fetch the collection of the option definitions for server1, server2
+    // and server3. The server3 does not have an explicit option definition, so
+    // for this server we should get the definition associated with "all" servers.
+    EXPECT_NO_THROW(
+        returned_option_defs = cbptr_->getAllOptionDefs6(ServerSelector::
+                                                         MULTIPLE({ "server1", "server2",
+                                                                    "server3" }));
+    );
+    ASSERT_EQ(3, returned_option_defs.size());
+
+    // Check that expected option definitions have been returned.
+    auto current_option = returned_option_defs.begin();
+    EXPECT_TRUE((*current_option)->equals(*option1));
+    EXPECT_TRUE((*(++current_option))->equals(*option2));
+    EXPECT_TRUE((*(++current_option))->equals(*option3));
+
+    // Try to fetch the collection of options specified for all servers.
+    // This excludes the options specific to server1 and server2. It returns
+    // only the common ones.
+    EXPECT_NO_THROW(
+        returned_option_defs = cbptr_->getAllOptionDefs6(ServerSelector::ALL());
+
+    );
+    ASSERT_EQ(1, returned_option_defs.size());
+    EXPECT_TRUE((*returned_option_defs.begin())->equals(*option3));
+
+    // Delete the server1. It should remove associations of this server with the
+    // option definitions and the option definition itself.
+    EXPECT_NO_THROW(cbptr_->deleteServer6(ServerTag("server1")));
+    EXPECT_NO_THROW(
+        returned_option_defs = cbptr_->getAllOptionDefs6(ServerSelector::ONE("server1"));
+
+    );
+    ASSERT_EQ(1, returned_option_defs.size());
+    EXPECT_TRUE((*returned_option_defs.begin())->equals(*option3));
+
+    {
+        SCOPED_TRACE("DELETE audit entry for the option definition after server deletion");
+        testNewAuditEntry("dhcp6_option_def",
+                          AuditEntry::ModificationType::DELETE,
+                          "deleting a server", ServerSelector::ONE("server1"),
+                          2, 1);
+    }
+
+    // Attempt to delete option definition for server1.
+    uint64_t deleted_num = 0;
+    EXPECT_NO_THROW(deleted_num = cbptr_->deleteOptionDef6(ServerSelector::ONE("server1"),
+                                                           option1->getCode(),
+                                                           option1->getOptionSpaceName()));
+    EXPECT_EQ(0, deleted_num);
+
+    // Deleting the existing option definition for server2 should succeed.
+    EXPECT_NO_THROW(deleted_num = cbptr_->deleteOptionDef6(ServerSelector::ONE("server2"),
+                                                           option2->getCode(),
+                                                           option2->getOptionSpaceName()));
+    EXPECT_EQ(1, deleted_num);
+
+    // Create this option definition again to test that deletion of all servers
+    // removes it too.
+    EXPECT_NO_THROW(cbptr_->createUpdateOptionDef6(ServerSelector::ONE("server2"),
+                                                   option2));
+
+    // Delete all servers, except 'all'.
+    EXPECT_NO_THROW(deleted_num = cbptr_->deleteAllServers6());
+    EXPECT_NO_THROW(
+        returned_option_defs = cbptr_->getAllOptionDefs6(ServerSelector::ALL());
+    );
+    EXPECT_EQ(1, deleted_num);
+    EXPECT_EQ(1, returned_option_defs.size());
+    EXPECT_TRUE((*returned_option_defs.begin())->equals(*option3));
+
+    {
+        SCOPED_TRACE("DELETE audit entry for the option definition after deletion of"
+                     " all servers");
+        testNewAuditEntry("dhcp6_option_def",
+                          AuditEntry::ModificationType::DELETE,
+                          "deleting all servers", ServerSelector::ONE("server2"),
+                          4, 1);
+    }
+}
+
+// Test that all option definitions can be fetched.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getAllOptionDefs6) {
+    // Insert test option definitions into the database. Note that the second
+    // option definition will overwrite the first option definition as they use
+    // the same code and space.
+    size_t updates_num = 0;
+    for (auto option_def : test_option_defs_) {
+        cbptr_->createUpdateOptionDef6(ServerSelector::ALL(), option_def);
+
+        // That option definition overrides the first one so the audit entry should
+        // indicate an update.
+        if (option_def->getName() == "bar") {
+            SCOPED_TRACE("UPDATE audit entry for the option definition " +
+                         option_def->getName());
+            testNewAuditEntry("dhcp6_option_def",
+                              AuditEntry::ModificationType::UPDATE,
+                              "option definition set");
+            ++updates_num;
+
+        } else {
+            SCOPED_TRACE("CREATE audit entry for the option definition " +
+                         option_def->getName());
+            testNewAuditEntry("dhcp6_option_def",
+                              AuditEntry::ModificationType::CREATE,
+                              "option definition set");
+        }
+    }
+
+    // Fetch all option_definitions.
+    OptionDefContainer option_defs = cbptr_->getAllOptionDefs6(ServerSelector::ALL());
+    ASSERT_EQ(test_option_defs_.size() - updates_num, option_defs.size());
+
+    // All option definitions should also be returned for explicitly specified
+    // server tag.
+    option_defs = cbptr_->getAllOptionDefs6(ServerSelector::ONE("server1"));
+    ASSERT_EQ(test_option_defs_.size() - updates_num, option_defs.size());
+
+    // See if option definitions are returned ok.
+    for (auto def = option_defs.begin(); def != option_defs.end(); ++def) {
+        ASSERT_EQ(1, (*def)->getServerTags().size());
+        EXPECT_EQ("all", (*def)->getServerTags().begin()->get());
+        bool success = false;
+        for (auto i = 1; i < test_option_defs_.size(); ++i) {
+            if ((*def)->equals(*test_option_defs_[i])) {
+                success = true;
+            }
+        }
+        ASSERT_TRUE(success) << "failed for option definition " << (*def)->getCode()
+            << ", option space " << (*def)->getOptionSpaceName();
+    }
+
+    // Deleting non-existing option definition should return 0.
+    EXPECT_EQ(0, cbptr_->deleteOptionDef6(ServerSelector::ALL(),
+                                          99, "non-exiting-space"));
+    // All option definitions should be still there.
+    ASSERT_EQ(test_option_defs_.size() - updates_num, option_defs.size());
+
+    // Should not delete option definition for explicit server tag
+    // because our option definition is for all servers.
+    EXPECT_EQ(0, cbptr_->deleteOptionDef6(ServerSelector::ONE("server1"),
+                                          test_option_defs_[1]->getCode(),
+                                          test_option_defs_[1]->getOptionSpaceName()));
+
+    // Same for all option definitions.
+    EXPECT_EQ(0, cbptr_->deleteAllOptionDefs6(ServerSelector::ONE("server1")));
+
+    // Delete one of the option definitions and see if it is gone.
+    EXPECT_EQ(1, cbptr_->deleteOptionDef6(ServerSelector::ALL(),
+                                          test_option_defs_[2]->getCode(),
+                                          test_option_defs_[2]->getOptionSpaceName()));
+    ASSERT_FALSE(cbptr_->getOptionDef6(ServerSelector::ALL(),
+                                       test_option_defs_[2]->getCode(),
+                                       test_option_defs_[2]->getOptionSpaceName()));
+
+    {
+        SCOPED_TRACE("DELETE audit entry for the first option definition");
+        testNewAuditEntry("dhcp6_option_def",
+                          AuditEntry::ModificationType::DELETE,
+                          "option definition deleted");
+    }
+
+    // Delete all remaining option definitions.
+    EXPECT_EQ(2, cbptr_->deleteAllOptionDefs6(ServerSelector::ALL()));
+    option_defs = cbptr_->getAllOptionDefs6(ServerSelector::ALL());
+    ASSERT_TRUE(option_defs.empty());
+
+    {
+        SCOPED_TRACE("DELETE audit entries for the remaining option definitions");
+        // The last parameter indicates that we expect two new audit entries.
+        testNewAuditEntry("dhcp6_option_def",
+                          AuditEntry::ModificationType::DELETE,
+                          "deleted all option definitions",
+                          ServerSelector::ALL(), 2);
+    }
+}
+
+// Test that option definitions modified after given time can be fetched.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getModifiedOptionDefs6) {
+    // Explicitly set timestamps of option definitions. First option
+    // definition has a timestamp pointing to the future. Second option
+    // definition has timestamp pointing to the past (yesterday).
+    // Third option definitions has a timestamp pointing to the
+    // past (an hour ago).
+    test_option_defs_[1]->setModificationTime(timestamps_["tomorrow"]);
+    test_option_defs_[2]->setModificationTime(timestamps_["yesterday"]);
+    test_option_defs_[3]->setModificationTime(timestamps_["today"]);
+
+    // Insert option definitions into the database.
+    for (int i = 1; i < test_networks_.size(); ++i) {
+        cbptr_->createUpdateOptionDef6(ServerSelector::ALL(),
+                                       test_option_defs_[i]);
+    }
+
+    // Fetch option definitions with timestamp later than today. Only one
+    // option definition should be returned.
+    OptionDefContainer
+        option_defs = cbptr_->getModifiedOptionDefs6(ServerSelector::ALL(),
+                                                     timestamps_["after today"]);
+    ASSERT_EQ(1, option_defs.size());
+
+    // Fetch option definitions with timestamp later than yesterday. We
+    // should get two option definitions.
+    option_defs = cbptr_->getModifiedOptionDefs6(ServerSelector::ALL(),
+                                                 timestamps_["after yesterday"]);
+    ASSERT_EQ(2, option_defs.size());
+
+    // Fetch option definitions with timestamp later than tomorrow. Nothing
+    // should be returned.
+    option_defs = cbptr_->getModifiedOptionDefs6(ServerSelector::ALL(),
+                                              timestamps_["after tomorrow"]);
+    ASSERT_TRUE(option_defs.empty());
+}
+
+// This test verifies that global option can be added, updated and deleted.
+TEST_F(PgSqlConfigBackendDHCPv6Test, createUpdateDeleteOption6) {
+    // Add option to the database.
+    OptionDescriptorPtr opt_posix_timezone = test_options_[0];
+    cbptr_->createUpdateOption6(ServerSelector::ALL(),
+                                opt_posix_timezone);
+
+    // Make sure we can retrieve this option and that it is equal to the
+    // option we have inserted into the database.
+    OptionDescriptorPtr returned_opt_posix_timezone =
+        cbptr_->getOption6(ServerSelector::ALL(),
+                           opt_posix_timezone->option_->getType(),
+                           opt_posix_timezone->space_name_);
+    ASSERT_TRUE(returned_opt_posix_timezone);
+
+    {
+        SCOPED_TRACE("verify created option");
+        testOptionsEquivalent(*opt_posix_timezone,
+                              *returned_opt_posix_timezone);
+    }
+
+    {
+        SCOPED_TRACE("CREATE audit entry for an option");
+        testNewAuditEntry("dhcp6_options",
+                          AuditEntry::ModificationType::CREATE,
+                          "global option set");
+    }
+
+    // Modify option and update it in the database.
+    opt_posix_timezone->persistent_ = !opt_posix_timezone->persistent_;
+    cbptr_->createUpdateOption6(ServerSelector::ALL(),
+                                opt_posix_timezone);
+
+    // Retrieve the option again and make sure that updates were
+    // properly propagated to the database. Use explicit server selector
+    // which should also return this option.
+    returned_opt_posix_timezone = cbptr_->getOption6(ServerSelector::ONE("server1"),
+                                                     opt_posix_timezone->option_->getType(),
+                                                     opt_posix_timezone->space_name_);
+    ASSERT_TRUE(returned_opt_posix_timezone);
+
+    {
+        SCOPED_TRACE("verify updated option");
+        testOptionsEquivalent(*opt_posix_timezone,
+                              *returned_opt_posix_timezone);
+    }
+
+    {
+        SCOPED_TRACE("UPDATE audit entry for an option");
+        testNewAuditEntry("dhcp6_options",
+                          AuditEntry::ModificationType::UPDATE,
+                          "global option set");
+    }
+
+    // Deleting an option with explicitly specified server tag should fail.
+    EXPECT_EQ(0, cbptr_->deleteOption6(ServerSelector::ONE("server1"),
+                                       opt_posix_timezone->option_->getType(),
+                                       opt_posix_timezone->space_name_));
+
+    // Deleting option for all servers should succeed.
+    EXPECT_EQ(1, cbptr_->deleteOption6(ServerSelector::ALL(),
+                                       opt_posix_timezone->option_->getType(),
+                                       opt_posix_timezone->space_name_));
+
+    EXPECT_FALSE(cbptr_->getOption6(ServerSelector::ALL(),
+                                    opt_posix_timezone->option_->getType(),
+                                    opt_posix_timezone->space_name_));
+
+    {
+        SCOPED_TRACE("DELETE audit entry for an option");
+        testNewAuditEntry("dhcp6_options",
+                          AuditEntry::ModificationType::DELETE,
+                          "global option deleted");
+    }
+}
+
+// This test verifies that it is possible to differentiate between the
+// global options by server tag and that the option specified for the
+// particular server overrides the value specified for all servers.
+TEST_F(PgSqlConfigBackendDHCPv6Test, globalOptions6WithServerTags) {
+    OptionDescriptorPtr opt_timezone1 = test_options_[0];
+    OptionDescriptorPtr opt_timezone2 = test_options_[6];
+    OptionDescriptorPtr opt_timezone3 = test_options_[7];
+
+    EXPECT_THROW(cbptr_->createUpdateOption6(ServerSelector::ONE("server1"),
+                                             opt_timezone1),
+                 NullKeyError);
+
+    // Create two servers.
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[1]));
+    {
+        SCOPED_TRACE("server1 is created");
+        testNewAuditEntry("dhcp6_server",
+                          AuditEntry::ModificationType::CREATE,
+                          "server set");
+    }
+
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[2]));
+    {
+        SCOPED_TRACE("server2 is created");
+        testNewAuditEntry("dhcp6_server",
+                          AuditEntry::ModificationType::CREATE,
+                          "server set");
+    }
+
+    EXPECT_NO_THROW(cbptr_->createUpdateOption6(ServerSelector::ONE("server1"),
+                                                opt_timezone1));
+    {
+        SCOPED_TRACE("global option for server1 is set");
+        // The value of 3 means there should be 3 audit entries available for the
+        // server1, two that indicate creation of the servers and one that we
+        // validate, which sets the global option.
+        testNewAuditEntry("dhcp6_options",
+                          AuditEntry::ModificationType::CREATE,
+                          "global option set",
+                          ServerSelector::ONE("server1"),
+                          3, 1);
+
+    }
+
+    EXPECT_NO_THROW(cbptr_->createUpdateOption6(ServerSelector::ONE("server2"),
+                                                opt_timezone2));
+    {
+        SCOPED_TRACE("global option for server2 is set");
+        // Same as in case of the server1, there should be 3 audit entries and
+        // we validate one of them.
+        testNewAuditEntry("dhcp6_options",
+                          AuditEntry::ModificationType::CREATE,
+                          "global option set",
+                          ServerSelector::ONE("server2"),
+                          3, 1);
+
+    }
+
+    EXPECT_NO_THROW(cbptr_->createUpdateOption6(ServerSelector::ALL(),
+                                                opt_timezone3));
+    {
+        SCOPED_TRACE("global option for all servers is set");
+        // There should be one new audit entry for all servers. It logs
+        // the insertion of the global option.
+        testNewAuditEntry("dhcp6_options",
+                          AuditEntry::ModificationType::CREATE,
+                          "global option set",
+                          ServerSelector::ALL(),
+                          1, 1);
+
+    }
+
+    OptionDescriptorPtr returned_option;
+
+    // Try to fetch the option specified for all servers. It should return
+    // the third option.
+    EXPECT_NO_THROW(
+        returned_option = cbptr_->getOption6(ServerSelector::ALL(),
+                                             opt_timezone3->option_->getType(),
+                                             opt_timezone3->space_name_);
+    );
+    ASSERT_TRUE(returned_option);
+    testOptionsEquivalent(*opt_timezone3, *returned_option);
+
+    // Try to fetch the option specified for the server1. It should override the
+    // option specified for all servers.
+    EXPECT_NO_THROW(
+        returned_option = cbptr_->getOption6(ServerSelector::ONE("server1"),
+                                             opt_timezone1->option_->getType(),
+                                             opt_timezone1->space_name_);
+    );
+    ASSERT_TRUE(returned_option);
+    testOptionsEquivalent(*opt_timezone1, *returned_option);
+
+    // The same in case of the server2.
+    EXPECT_NO_THROW(
+        returned_option = cbptr_->getOption6(ServerSelector::ONE("server2"),
+                                             opt_timezone2->option_->getType(),
+                                             opt_timezone2->space_name_);
+    );
+    ASSERT_TRUE(returned_option);
+    testOptionsEquivalent(*opt_timezone2, *returned_option);
+
+    OptionContainer returned_options;
+
+    // Try to fetch the collection of global options for the server1, server2
+    // and server3. The server3 does not have an explicit value so for this server
+    // we should get the option associated with "all" servers.
+    EXPECT_NO_THROW(
+        returned_options = cbptr_->getAllOptions6(ServerSelector::
+                                                  MULTIPLE({ "server1", "server2",
+                                                             "server3" }));
+    );
+    ASSERT_EQ(3, returned_options.size());
+
+    // Check that expected options have been returned.
+    auto current_option = returned_options.begin();
+    testOptionsEquivalent(*opt_timezone1, *current_option);
+    testOptionsEquivalent(*opt_timezone2, *(++current_option));
+    testOptionsEquivalent(*opt_timezone3, *(++current_option));
+
+    // Try to fetch the collection of options specified for all servers.
+    // This excludes the options specific to server1 and server2. It returns
+    // only the common ones.
+    EXPECT_NO_THROW(
+        returned_options = cbptr_->getAllOptions6(ServerSelector::ALL());
+    );
+    ASSERT_EQ(1, returned_options.size());
+    testOptionsEquivalent(*opt_timezone3, *returned_options.begin());
+
+    // Delete the server1. It should remove associations of this server with the
+    // option and the option itself.
+    EXPECT_NO_THROW(cbptr_->deleteServer6(ServerTag("server1")));
+    EXPECT_NO_THROW(
+        returned_options = cbptr_->getAllOptions6(ServerSelector::ONE("server1"));
+    );
+    ASSERT_EQ(1, returned_options.size());
+    testOptionsEquivalent(*opt_timezone3, *returned_options.begin());
+
+    {
+        SCOPED_TRACE("DELETE audit entry for the global option after server deletion");
+        testNewAuditEntry("dhcp6_options",
+                          AuditEntry::ModificationType::DELETE,
+                          "deleting a server", ServerSelector::ONE("server1"),
+                          2, 1);
+    }
+
+    // Attempt to delete global option for server1.
+    uint64_t deleted_num = 0;
+    EXPECT_NO_THROW(deleted_num = cbptr_->deleteOption6(ServerSelector::ONE("server1"),
+                                                        opt_timezone1->option_->getType(),
+                                                        opt_timezone1->space_name_));
+    EXPECT_EQ(0, deleted_num);
+
+    // Deleting the existing option for server2 should succeed.
+    EXPECT_NO_THROW(deleted_num = cbptr_->deleteOption6(ServerSelector::ONE("server2"),
+                                                        opt_timezone2->option_->getType(),
+                                                        opt_timezone2->space_name_));
+    EXPECT_EQ(1, deleted_num);
+
+    // Create this option again to test that deletion of all servers removes it too.
+    EXPECT_NO_THROW(cbptr_->createUpdateOption6(ServerSelector::ONE("server2"),
+                                                opt_timezone2));
+
+    // Delete all servers, except 'all'.
+    EXPECT_NO_THROW(deleted_num = cbptr_->deleteAllServers6());
+    EXPECT_NO_THROW(
+        returned_options = cbptr_->getAllOptions6(ServerSelector::ALL());
+    );
+    EXPECT_EQ(1, deleted_num);
+    ASSERT_EQ(1, returned_options.size());
+    testOptionsEquivalent(*opt_timezone3, *returned_options.begin());
+
+    {
+        SCOPED_TRACE("DELETE audit entry for the global option after deletion of"
+                     " all servers");
+        testNewAuditEntry("dhcp6_options",
+                          AuditEntry::ModificationType::DELETE,
+                          "deleting all servers", ServerSelector::ONE("server2"),
+                          4, 1);
+    }
+}
+
+// This test verifies that all global options can be retrieved.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getAllOptions6) {
+    // Add three global options to the database.
+    cbptr_->createUpdateOption6(ServerSelector::ALL(),
+                                test_options_[0]);
+    cbptr_->createUpdateOption6(ServerSelector::ALL(),
+                                test_options_[1]);
+    cbptr_->createUpdateOption6(ServerSelector::ALL(),
+                                test_options_[5]);
+
+    // Retrieve all these options.
+    OptionContainer returned_options = cbptr_->getAllOptions6(ServerSelector::ALL());
+    ASSERT_EQ(3, returned_options.size());
+
+    // Fetching global options with explicitly specified server tag should return
+    // the same result.
+    returned_options = cbptr_->getAllOptions6(ServerSelector::ONE("server1"));
+    ASSERT_EQ(3, returned_options.size());
+
+    // Get the container index used to search options by option code.
+    const OptionContainerTypeIndex& index = returned_options.get<1>();
+
+    // Verify that all options we put into the database were
+    // returned.
+    {
+        SCOPED_TRACE("verify test_options_[0]");
+        auto option0 = index.find(test_options_[0]->option_->getType());
+        ASSERT_FALSE(option0 == index.end());
+        testOptionsEquivalent(*test_options_[0], *option0);
+        EXPECT_GT(option0->getId(), 0);
+        ASSERT_EQ(1, option0->getServerTags().size());
+        EXPECT_EQ("all", option0->getServerTags().begin()->get());
+    }
+
+    {
+        SCOPED_TRACE("verify test_options_[1]");
+        auto option1 = index.find(test_options_[1]->option_->getType());
+        ASSERT_FALSE(option1 == index.end());
+        testOptionsEquivalent(*test_options_[1], *option1);
+        EXPECT_GT(option1->getId(), 0);
+        ASSERT_EQ(1, option1->getServerTags().size());
+        EXPECT_EQ("all", option1->getServerTags().begin()->get());
+    }
+
+    {
+        SCOPED_TRACE("verify test_options_[5]");
+        auto option5 = index.find(test_options_[5]->option_->getType());
+        ASSERT_FALSE(option5 == index.end());
+        testOptionsEquivalent(*test_options_[5], *option5);
+        EXPECT_GT(option5->getId(), 0);
+        ASSERT_EQ(1, option5->getServerTags().size());
+        EXPECT_EQ("all", option5->getServerTags().begin()->get());
+    }
+}
+
+// This test verifies that modified global options can be retrieved.
+TEST_F(PgSqlConfigBackendDHCPv6Test, getModifiedOptions6) {
+    // Assign timestamps to the options we're going to store in the
+    // database.
+    test_options_[0]->setModificationTime(timestamps_["tomorrow"]);
+    test_options_[1]->setModificationTime(timestamps_["yesterday"]);
+    test_options_[5]->setModificationTime(timestamps_["today"]);
+
+    // Put options into the database.
+    cbptr_->createUpdateOption6(ServerSelector::ALL(),
+                                test_options_[0]);
+    cbptr_->createUpdateOption6(ServerSelector::ALL(),
+                                test_options_[1]);
+    cbptr_->createUpdateOption6(ServerSelector::ALL(),
+                                test_options_[5]);
+
+    // Get options with the timestamp later than today. Only
+    // one option should be returned.
+    OptionContainer returned_options =
+        cbptr_->getModifiedOptions6(ServerSelector::ALL(),
+                                    timestamps_["after today"]);
+    ASSERT_EQ(1, returned_options.size());
+
+    // Fetching modified options with explicitly specified server selector
+    // should return the same result.
+    returned_options = cbptr_->getModifiedOptions6(ServerSelector::ONE("server1"),
+                                                   timestamps_["after today"]);
+    ASSERT_EQ(1, returned_options.size());
+
+    // The returned option should be the one with the timestamp
+    // set to tomorrow.
+    const OptionContainerTypeIndex& index = returned_options.get<1>();
+    auto option0 = index.find(test_options_[0]->option_->getType());
+    ASSERT_FALSE(option0 == index.end());
+    {
+        SCOPED_TRACE("verify returned option");
+        testOptionsEquivalent(*test_options_[0], *option0);
+    }
+}
+
+// This test verifies that subnet level option can be added, updated and
+// deleted.
+TEST_F(PgSqlConfigBackendDHCPv6Test, createUpdateDeleteSubnetOption6) {
+    // Insert new subnet.
+    Subnet6Ptr subnet = test_subnets_[1];
+    cbptr_->createUpdateSubnet6(ServerSelector::ALL(), subnet);
+
+    // Fetch this subnet by subnet identifier.
+    Subnet6Ptr returned_subnet = cbptr_->getSubnet6(ServerSelector::ALL(),
+                                                    subnet->getID());
+    ASSERT_TRUE(returned_subnet);
+
+    {
+        SCOPED_TRACE("CREATE audit entry for a new subnet");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::CREATE,
+                          "subnet set");
+    }
+
+    // The inserted subnet contains four options.
+    ASSERT_EQ(4, countRows("dhcp6_options"));
+
+    OptionDescriptorPtr opt_posix_timezone = test_options_[0];
+    cbptr_->createUpdateOption6(ServerSelector::ANY(), subnet->getID(),
+                                opt_posix_timezone);
+
+    returned_subnet = cbptr_->getSubnet6(ServerSelector::ALL(),
+                                         subnet->getID());
+    ASSERT_TRUE(returned_subnet);
+
+    OptionDescriptor returned_opt_posix_timezone =
+        returned_subnet->getCfgOption()->get(DHCP6_OPTION_SPACE, D6O_NEW_POSIX_TIMEZONE);
+    ASSERT_TRUE(returned_opt_posix_timezone.option_);
+
+    {
+        SCOPED_TRACE("verify returned option");
+        testOptionsEquivalent(*opt_posix_timezone, returned_opt_posix_timezone);
+        EXPECT_GT(returned_opt_posix_timezone.getId(), 0);
+    }
+
+    {
+        SCOPED_TRACE("UPDATE audit entry for an added subnet option");
+        // Instead of adding an audit entry for an option we add an audit
+        // entry for the entire subnet so as the server refreshes the
+        // subnet with the new option. Note that the server doesn't
+        // have means to retrieve only the newly added option.
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::UPDATE,
+                          "subnet specific option set");
+    }
+
+    // We have added one option to the existing subnet. We should now have
+    // five options.
+    ASSERT_EQ(5, countRows("dhcp6_options"));
+
+    opt_posix_timezone->persistent_ = !opt_posix_timezone->persistent_;
+    cbptr_->createUpdateOption6(ServerSelector::ANY(), subnet->getID(),
+                                opt_posix_timezone);
+
+    returned_subnet = cbptr_->getSubnet6(ServerSelector::ALL(),
+                                         subnet->getID());
+    ASSERT_TRUE(returned_subnet);
+    returned_opt_posix_timezone =
+        returned_subnet->getCfgOption()->get(DHCP6_OPTION_SPACE, D6O_NEW_POSIX_TIMEZONE);
+    ASSERT_TRUE(returned_opt_posix_timezone.option_);
+
+    {
+        SCOPED_TRACE("verify returned option with modified persistence");
+        testOptionsEquivalent(*opt_posix_timezone, returned_opt_posix_timezone);
+    }
+
+    {
+        SCOPED_TRACE("UPDATE audit entry for an updated subnet option");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::UPDATE,
+                          "subnet specific option set");
+    }
+
+    // Updating the option should replace the existing instance with the new
+    // instance. Therefore, we should still have five options.
+    ASSERT_EQ(5, countRows("dhcp6_options"));
+
+    // It should succeed for any server.
+    EXPECT_EQ(1, cbptr_->deleteOption6(ServerSelector::ANY(), subnet->getID(),
+                                       opt_posix_timezone->option_->getType(),
+                                       opt_posix_timezone->space_name_));
+
+    returned_subnet = cbptr_->getSubnet6(ServerSelector::ALL(),
+                                         subnet->getID());
+    ASSERT_TRUE(returned_subnet);
+
+    EXPECT_FALSE(returned_subnet->getCfgOption()->get(DHCP6_OPTION_SPACE, D6O_NEW_POSIX_TIMEZONE).option_);
+
+    {
+        SCOPED_TRACE("UPDATE audit entry for a deleted subnet option");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::UPDATE,
+                          "subnet specific option deleted");
+    }
+
+    // We should have only four options after deleting one of them.
+    ASSERT_EQ(4, countRows("dhcp6_options"));
+}
+
+// This test verifies that option can be inserted, updated and deleted
+// from the pool.
+TEST_F(PgSqlConfigBackendDHCPv6Test, createUpdateDeletePoolOption6) {
+    // Insert new subnet.
+    Subnet6Ptr subnet = test_subnets_[1];
+    cbptr_->createUpdateSubnet6(ServerSelector::ALL(), subnet);
+
+    {
+        SCOPED_TRACE("CREATE audit entry for a subnet");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::CREATE,
+                          "subnet set");
+    }
+
+    // Inserted subnet has four options.
+    ASSERT_EQ(4, countRows("dhcp6_options"));
+
+    // Add an option into the pool.
+    const PoolPtr pool = subnet->getPool(Lease::TYPE_NA,
+                                         IOAddress("2001:db8::10"));
+    ASSERT_TRUE(pool);
+    OptionDescriptorPtr opt_posix_timezone = test_options_[0];
+    cbptr_->createUpdateOption6(ServerSelector::ANY(),
+                                pool->getFirstAddress(),
+                                pool->getLastAddress(),
+                                opt_posix_timezone);
+
+    // Query for a subnet.
+    Subnet6Ptr returned_subnet = cbptr_->getSubnet6(ServerSelector::ALL(),
+                                                    subnet->getID());
+    ASSERT_TRUE(returned_subnet);
+
+    // The returned subnet should include our pool.
+    const PoolPtr returned_pool = returned_subnet->getPool(Lease::TYPE_NA,
+                                                           IOAddress("2001:db8::10"));
+    ASSERT_TRUE(returned_pool);
+
+    // The pool should contain option we added earlier.
+    OptionDescriptor returned_opt_posix_timezone =
+        returned_pool->getCfgOption()->get(DHCP6_OPTION_SPACE, D6O_NEW_POSIX_TIMEZONE);
+    ASSERT_TRUE(returned_opt_posix_timezone.option_);
+
+    {
+        SCOPED_TRACE("verify returned pool option");
+        testOptionsEquivalent(*opt_posix_timezone, returned_opt_posix_timezone);
+        EXPECT_GT(returned_opt_posix_timezone.getId(), 0);
+    }
+
+    {
+        SCOPED_TRACE("UPDATE audit entry for a subnet after adding an option "
+                     "to the address pool");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::UPDATE,
+                          "address pool specific option set");
+    }
+
+    // With the newly inserted option we should now have five options.
+    ASSERT_EQ(5, countRows("dhcp6_options"));
+
+    // Modify the option and update it in the database.
+    opt_posix_timezone->persistent_ = !opt_posix_timezone->persistent_;
+    cbptr_->createUpdateOption6(ServerSelector::ANY(),
+                                pool->getFirstAddress(),
+                                pool->getLastAddress(),
+                                opt_posix_timezone);
+
+    // Fetch the subnet and the corresponding pool.
+    returned_subnet = cbptr_->getSubnet6(ServerSelector::ALL(),
+                                         subnet->getID());
+    ASSERT_TRUE(returned_subnet);
+    const PoolPtr returned_pool1 = returned_subnet->getPool(Lease::TYPE_NA,
+                                                            IOAddress("2001:db8::10"));
+    ASSERT_TRUE(returned_pool1);
+
+    // Test that the option has been correctly updated in the database.
+    returned_opt_posix_timezone =
+        returned_pool1->getCfgOption()->get(DHCP6_OPTION_SPACE, D6O_NEW_POSIX_TIMEZONE);
+    ASSERT_TRUE(returned_opt_posix_timezone.option_);
+
+    {
+        SCOPED_TRACE("verify updated option with modified persistence");
+        testOptionsEquivalent(*opt_posix_timezone, returned_opt_posix_timezone);
+    }
+
+    {
+        SCOPED_TRACE("UPDATE audit entry for a subnet when updating "
+                     "address  pool specific option");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::UPDATE,
+                          "address pool specific option set");
+    }
+
+    // The new option instance should replace the existing one, so we should
+    // still have five options.
+    ASSERT_EQ(5, countRows("dhcp6_options"));
+
+    // Delete option for any server should succeed.
+    EXPECT_EQ(1, cbptr_->deleteOption6(ServerSelector::ANY(),
+                                       pool->getFirstAddress(),
+                                       pool->getLastAddress(),
+                                       opt_posix_timezone->option_->getType(),
+                                       opt_posix_timezone->space_name_));
+
+    // Fetch the subnet and the pool from the database again to make sure
+    // that the option is really gone.
+    returned_subnet = cbptr_->getSubnet6(ServerSelector::ALL(),
+                                         subnet->getID());
+    ASSERT_TRUE(returned_subnet);
+    const PoolPtr returned_pool2 = returned_subnet->getPool(Lease::TYPE_NA,
+                                                            IOAddress("2001:db8::10"));
+    ASSERT_TRUE(returned_pool2);
+
+    // Option should be gone.
+    EXPECT_FALSE(returned_pool2->getCfgOption()->get(DHCP6_OPTION_SPACE,
+                                                     D6O_NEW_POSIX_TIMEZONE).option_);
+
+    {
+        SCOPED_TRACE("UPDATE audit entry for a subnet when deleting "
+                     "address pool specific option");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::UPDATE,
+                          "address pool specific option deleted");
+    }
+
+    // The option has been deleted so the number of options should now
+    // be down to 4.
+    EXPECT_EQ(4, countRows("dhcp6_options"));
+}
+
+// This test verifies that option can be inserted, updated and deleted
+// from the pd pool.
+TEST_F(PgSqlConfigBackendDHCPv6Test, createUpdateDeletePdPoolOption6) {
+    // Insert new subnet.
+    Subnet6Ptr subnet = test_subnets_[1];
+    cbptr_->createUpdateSubnet6(ServerSelector::ALL(), subnet);
+
+    {
+        SCOPED_TRACE("CREATE audit entry for a subnet");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::CREATE,
+                          "subnet set");
+    }
+
+    // Inserted subnet has four options.
+    ASSERT_EQ(4, countRows("dhcp6_options"));
+
+    // Add an option into the pd pool.
+    const PoolPtr pd_pool = subnet->getPool(Lease::TYPE_PD,
+                                            IOAddress("2001:db8:a:10::"));
+    ASSERT_TRUE(pd_pool);
+    OptionDescriptorPtr opt_posix_timezone = test_options_[0];
+    int pd_pool_len = prefixLengthFromRange(pd_pool->getFirstAddress(),
+                                            pd_pool->getLastAddress());
+    cbptr_->createUpdateOption6(ServerSelector::ANY(),
+                                pd_pool->getFirstAddress(),
+                                static_cast<uint8_t>(pd_pool_len),
+                                opt_posix_timezone);
+
+    // Query for a subnet.
+    Subnet6Ptr returned_subnet = cbptr_->getSubnet6(ServerSelector::ALL(),
+                                                    subnet->getID());
+    ASSERT_TRUE(returned_subnet);
+
+    // The returned subnet should include our pool.
+    const PoolPtr returned_pd_pool =
+        returned_subnet->getPool(Lease::TYPE_PD, IOAddress("2001:db8:a:10::"));
+    ASSERT_TRUE(returned_pd_pool);
+
+    // The pd pool should contain option we added earlier.
+    OptionDescriptor returned_opt_posix_timezone =
+        returned_pd_pool->getCfgOption()->get(DHCP6_OPTION_SPACE,
+                                              D6O_NEW_POSIX_TIMEZONE);
+    ASSERT_TRUE(returned_opt_posix_timezone.option_);
+
+    {
+        SCOPED_TRACE("verify returned pool option");
+        testOptionsEquivalent(*opt_posix_timezone, returned_opt_posix_timezone);
+        EXPECT_GT(returned_opt_posix_timezone.getId(), 0);
+    }
+
+    {
+        SCOPED_TRACE("UPDATE audit entry for a subnet after adding an option "
+                     "to the prefix delegation pool");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::UPDATE,
+                          "prefix delegation pool specific option set");
+    }
+
+    // With the newly inserted option we should now have five options.
+    ASSERT_EQ(5, countRows("dhcp6_options"));
+
+    // Modify the option and update it in the database.
+    opt_posix_timezone->persistent_ = !opt_posix_timezone->persistent_;
+    cbptr_->createUpdateOption6(ServerSelector::ANY(),
+                                pd_pool->getFirstAddress(),
+                                static_cast<uint8_t>(pd_pool_len),
+                                opt_posix_timezone);
+
+    // Fetch the subnet and the corresponding pd pool.
+    returned_subnet = cbptr_->getSubnet6(ServerSelector::ALL(),
+                                         subnet->getID());
+    ASSERT_TRUE(returned_subnet);
+    const PoolPtr returned_pd_pool1 =
+        returned_subnet->getPool(Lease::TYPE_PD, IOAddress("2001:db8:a:10::"));
+    ASSERT_TRUE(returned_pd_pool1);
+
+    // Test that the option has been correctly updated in the database.
+    returned_opt_posix_timezone =
+        returned_pd_pool1->getCfgOption()->get(DHCP6_OPTION_SPACE,
+                                               D6O_NEW_POSIX_TIMEZONE);
+    ASSERT_TRUE(returned_opt_posix_timezone.option_);
+
+    {
+        SCOPED_TRACE("verify updated option with modified persistence");
+        testOptionsEquivalent(*opt_posix_timezone, returned_opt_posix_timezone);
+    }
+
+    {
+        SCOPED_TRACE("UPDATE audit entry for a subnet when updating "
+                     "prefix delegation pool specific option");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::UPDATE,
+                          "prefix delegation pool specific option set");
+    }
+
+    // The new option instance should replace the existing one, so we should
+    // still have five options.
+    ASSERT_EQ(5, countRows("dhcp6_options"));
+
+    // Delete option for any server should succeed.
+    EXPECT_EQ(1, cbptr_->deleteOption6(ServerSelector::ANY(),
+                                       pd_pool->getFirstAddress(),
+                                       static_cast<uint8_t>(pd_pool_len),
+                                       opt_posix_timezone->option_->getType(),
+                                       opt_posix_timezone->space_name_));
+
+    // Fetch the subnet and the pool from the database again to make sure
+    // that the option is really gone.
+    returned_subnet = cbptr_->getSubnet6(ServerSelector::ALL(),
+                                         subnet->getID());
+    ASSERT_TRUE(returned_subnet);
+    const PoolPtr returned_pd_pool2 =
+        returned_subnet->getPool(Lease::TYPE_PD, IOAddress("2001:db8:a:10::"));
+    ASSERT_TRUE(returned_pd_pool2);
+
+    // Option should be gone.
+    EXPECT_FALSE(returned_pd_pool2->getCfgOption()->get(DHCP6_OPTION_SPACE,
+                                                        D6O_NEW_POSIX_TIMEZONE).option_);
+
+    {
+        SCOPED_TRACE("UPDATE audit entry for a subnet when deleting "
+                     "prefix delegation pool specific option");
+        testNewAuditEntry("dhcp6_subnet",
+                          AuditEntry::ModificationType::UPDATE,
+                          "prefix delegation pool specific option deleted");
+    }
+
+    // The option has been deleted so the number of options should now
+    // be down to 4.
+    EXPECT_EQ(4, countRows("dhcp6_options"));
+}
+
+// This test verifies that shared network level option can be added,
+// updated and deleted.
+TEST_F(PgSqlConfigBackendDHCPv6Test, createUpdateDeleteSharedNetworkOption6) {
+    // Insert new shared network.
+    SharedNetwork6Ptr shared_network = test_networks_[1];
+    cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(),
+                                       shared_network);
+
+    // Fetch this shared network by name.
+    SharedNetwork6Ptr returned_network =
+        cbptr_->getSharedNetwork6(ServerSelector::ALL(),
+                                  shared_network->getName());
+    ASSERT_TRUE(returned_network);
+
+    {
+        SCOPED_TRACE("CREATE audit entry for the new shared network");
+        testNewAuditEntry("dhcp6_shared_network",
+                          AuditEntry::ModificationType::CREATE,
+                          "shared network set");
+    }
+
+    // The inserted shared network has no options.
+    ASSERT_EQ(0, countRows("dhcp6_options"));
+
+    OptionDescriptorPtr opt_posix_timezone = test_options_[0];
+    cbptr_->createUpdateOption6(ServerSelector::ANY(),
+                                shared_network->getName(),
+                                opt_posix_timezone);
+
+    returned_network = cbptr_->getSharedNetwork6(ServerSelector::ALL(),
+                                                shared_network->getName());
+    ASSERT_TRUE(returned_network);
+
+    OptionDescriptor returned_opt_posix_timezone =
+        returned_network->getCfgOption()->get(DHCP6_OPTION_SPACE, D6O_NEW_POSIX_TIMEZONE);
+    ASSERT_TRUE(returned_opt_posix_timezone.option_);
+
+    {
+        SCOPED_TRACE("verify returned option");
+        testOptionsEquivalent(*opt_posix_timezone, returned_opt_posix_timezone);
+        EXPECT_GT(returned_opt_posix_timezone.getId(), 0);
+    }
+
+    {
+        SCOPED_TRACE("UPDATE audit entry for the added shared network option");
+        // Instead of adding an audit entry for an option we add an audit
+        // entry for the entire shared network so as the server refreshes the
+        // shared network with the new option. Note that the server doesn't
+        // have means to retrieve only the newly added option.
+        testNewAuditEntry("dhcp6_shared_network",
+                          AuditEntry::ModificationType::UPDATE,
+                          "shared network specific option set");
+    }
+
+    // One option should now be stored in the database.
+    ASSERT_EQ(1, countRows("dhcp6_options"));
+
+    opt_posix_timezone->persistent_ = !opt_posix_timezone->persistent_;
+    cbptr_->createUpdateOption6(ServerSelector::ANY(),
+                                shared_network->getName(),
+                                opt_posix_timezone);
+
+    returned_network = cbptr_->getSharedNetwork6(ServerSelector::ALL(),
+                                                 shared_network->getName());
+    ASSERT_TRUE(returned_network);
+    returned_opt_posix_timezone =
+        returned_network->getCfgOption()->get(DHCP6_OPTION_SPACE, D6O_NEW_POSIX_TIMEZONE);
+    ASSERT_TRUE(returned_opt_posix_timezone.option_);
+
+    {
+        SCOPED_TRACE("verify updated option with modified persistence");
+        testOptionsEquivalent(*opt_posix_timezone, returned_opt_posix_timezone);
+    }
+
+    {
+        SCOPED_TRACE("UPDATE audit entry for the updated shared network option");
+        testNewAuditEntry("dhcp6_shared_network",
+                          AuditEntry::ModificationType::UPDATE,
+                          "shared network specific option set");
+    }
+
+    // The new option instance should replace the existing option instance,
+    // so we should still have one option.
+    ASSERT_EQ(1, countRows("dhcp6_options"));
+
+    // Deleting an option for any server should succeed.
+    EXPECT_EQ(1, cbptr_->deleteOption6(ServerSelector::ANY(),
+                                       shared_network->getName(),
+                                       opt_posix_timezone->option_->getType(),
+                                       opt_posix_timezone->space_name_));
+    returned_network = cbptr_->getSharedNetwork6(ServerSelector::ALL(),
+                                                 shared_network->getName());
+    ASSERT_TRUE(returned_network);
+    EXPECT_FALSE(returned_network->getCfgOption()->get(DHCP6_OPTION_SPACE, D6O_NEW_POSIX_TIMEZONE).option_);
+
+    {
+        SCOPED_TRACE("UPDATE audit entry for the deleted shared network option");
+        testNewAuditEntry("dhcp6_shared_network",
+                          AuditEntry::ModificationType::UPDATE,
+                          "shared network specific option deleted");
+    }
+
+    // After deleting the option we should be back to 0.
+    EXPECT_EQ(0, countRows("dhcp6_options"));
+}
+
+// This test verifies that option id values in one subnet do
+// not impact options returned in subsequent subnets when
+// fetching subnets from the backend.
+TEST_F(PgSqlConfigBackendDHCPv6Test, subnetOptionIdOrder) {
+
+    // Add a network with two pools with two options each.
+    EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ALL(), test_subnets_[1]));
+    EXPECT_EQ(2, countRows("dhcp6_pool"));
+    EXPECT_EQ(4, countRows("dhcp6_options"));
+
+    // Add second subnet with a single option. The number of options in the database
+    // should now be 3.
+    EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ALL(), test_subnets_[2]));
+    EXPECT_EQ(2, countRows("dhcp6_pool"));
+    EXPECT_EQ(5, countRows("dhcp6_options"));
+
+    // Now replace the first subnet with three options and two pools.  This will cause
+    // the option id values for this subnet to be larger than those in the second
+    // subnet.
+    EXPECT_NO_THROW(cbptr_->createUpdateSubnet6(ServerSelector::ALL(), test_subnets_[0]));
+    EXPECT_EQ(2, countRows("dhcp6_pool"));
+    EXPECT_EQ(4, countRows("dhcp6_options"));
+
+    // Now fetch all subnets.
+    Subnet6Collection subnets;
+    EXPECT_NO_THROW(subnets = cbptr_->getAllSubnets6(ServerSelector::ALL()));
+    ASSERT_EQ(2, subnets.size());
+
+    // Verify that the subnets returned are as expected.
+    for (auto subnet : subnets) {
+        ASSERT_EQ(1, subnet->getServerTags().size());
+        EXPECT_EQ("all", subnet->getServerTags().begin()->get());
+        if (subnet->getID() == 1024) {
+            EXPECT_EQ(test_subnets_[0]->toElement()->str(), subnet->toElement()->str());
+        } else if (subnet->getID() == 2048) {
+            EXPECT_EQ(test_subnets_[2]->toElement()->str(), subnet->toElement()->str());
+        } else {
+            ADD_FAILURE() << "unexpected subnet id:" << subnet->getID();
+        }
+    }
+}
+
+// This test verifies that option id values in one shared network do
+// not impact options returned in subsequent shared networks when
+// fetching shared networks from the backend.
+TEST_F(PgSqlConfigBackendDHCPv6Test, sharedNetworkOptionIdOrder) {
+    auto level1_options = test_networks_[0];
+    auto level1_no_options = test_networks_[1];
+    auto level2 = test_networks_[2];
+
+    // Insert two shared networks. We insert level1 without options first,
+    // then level2.
+    EXPECT_NO_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(),
+                                                       level1_no_options));
+
+    EXPECT_NO_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(),
+                                                       level2));
+    // Fetch all shared networks.
+    SharedNetwork6Collection networks =
+        cbptr_->getAllSharedNetworks6(ServerSelector::ALL());
+
+    ASSERT_EQ(2, networks.size());
+
+    // See if shared networks are returned ok.
+    for (auto i = 0; i < networks.size(); ++i) {
+        if (i == 0) {
+            // level1_no_options
+            EXPECT_EQ(level1_no_options->toElement()->str(),
+                  networks[i]->toElement()->str());
+        } else {
+            // bar
+            EXPECT_EQ(level2->toElement()->str(),
+                  networks[i]->toElement()->str());
+        }
+    }
+
+    EXPECT_NO_THROW(cbptr_->createUpdateSharedNetwork6(ServerSelector::ALL(),
+                                                       level1_options));
+
+    // Fetch all shared networks.
+    networks = cbptr_->getAllSharedNetworks6(ServerSelector::ALL());
+    ASSERT_EQ(2, networks.size());
+
+    // See if shared networks are returned ok.
+    for (auto i = 0; i < networks.size(); ++i) {
+        if (i == 0) {
+            // level1_no_options
+            EXPECT_EQ(level1_options->toElement()->str(),
+                  networks[i]->toElement()->str());
+        } else {
+            // bar
+            EXPECT_EQ(level2->toElement()->str(),
+                  networks[i]->toElement()->str());
+        }
+    }
+}
+
+/// This test verifies that audit entries can be retrieved from a given
+/// timestamp and id including when two entries can get the same timestamp.
+/// (either it is a common even and this should catch it, or it is a rare
+/// event and it does not matter).
+TEST_F(PgSqlConfigBackendDHCPv6Test, multipleAuditEntries) {
+    // Get current time.
+    boost::posix_time::ptime now = boost::posix_time::second_clock::local_time();
+
+    // Create a server.
+    EXPECT_NO_THROW(cbptr_->createUpdateServer6(test_servers_[1]));
+
+    // Create a global parameter and update it many times.
+    const ServerSelector& server_selector = ServerSelector::ALL();
+    StampedValuePtr param;
+    ElementPtr value;
+    for (int i = 0; i < 100; ++i) {
+        value = Element::create(i);
+        param = StampedValue::create("my-parameter", value);
+        cbptr_->createUpdateGlobalParameter6(server_selector, param);
+    }
+
+    // Get all audit entries from now.
+    AuditEntryCollection audit_entries =
+        cbptr_->getRecentAuditEntries(server_selector, now, 0);
+
+    // Check that partial retrieves return the right count.
+    auto& mod_time_idx = audit_entries.get<AuditEntryModificationTimeIdTag>();
+    for (auto it = mod_time_idx.begin(); it != mod_time_idx.end(); ++it) {
+        size_t partial_size =
+            cbptr_->getRecentAuditEntries(server_selector,
+                                          (*it)->getModificationTime(),
+                                          (*it)->getRevisionId()).size();
+        EXPECT_EQ(partial_size + 1,
+                  std::distance(it, mod_time_idx.end()));
+    }
+}
+
+class PgSqlConfigBackendDHCPv6DbLostCallbackTest : public ::testing::Test {
+public:
+    PgSqlConfigBackendDHCPv6DbLostCallbackTest()
+        : db_lost_callback_called_(0), db_recovered_callback_called_(0),
+          db_failed_callback_called_(0),
+          io_service_(boost::make_shared<isc::asiolink::IOService>()) {
+        isc::db::DatabaseConnection::db_lost_callback_ = 0;
+        isc::db::DatabaseConnection::db_recovered_callback_ = 0;
+        isc::db::DatabaseConnection::db_failed_callback_ = 0;
+        isc::dhcp::PgSqlConfigBackendImpl::setIOService(io_service_);
+        isc::dhcp::TimerMgr::instance()->setIOService(io_service_);
+        isc::dhcp::CfgMgr::instance().clear();
+    }
+
+    virtual ~PgSqlConfigBackendDHCPv6DbLostCallbackTest() {
+        isc::db::DatabaseConnection::db_lost_callback_ = 0;
+        isc::db::DatabaseConnection::db_recovered_callback_ = 0;
+        isc::db::DatabaseConnection::db_failed_callback_ = 0;
+        isc::dhcp::PgSqlConfigBackendImpl::setIOService(isc::asiolink::IOServicePtr());
+        isc::dhcp::TimerMgr::instance()->unregisterTimers();
+        isc::dhcp::CfgMgr::instance().clear();
+    }
+
+    /// @brief Prepares the class for a test.
+    ///
+    /// Invoked by gtest prior test entry, we create the
+    /// appropriate schema and create a basic DB manager to
+    /// wipe out any prior instance
+    virtual void SetUp() {
+        // Ensure we have the proper schema with no transient data.
+        createPgSQLSchema();
+        isc::dhcp::CfgMgr::instance().clear();
+        isc::dhcp::PgSqlConfigBackendDHCPv6::registerBackendType();
+    }
+
+    /// @brief Pre-text exit clean up
+    ///
+    /// Invoked by gtest upon test exit, we destroy the schema
+    /// we created.
+    virtual void TearDown() {
+        // If data wipe enabled, delete transient data otherwise destroy the schema
+        destroyPgSQLSchema();
+        isc::dhcp::CfgMgr::instance().clear();
+        isc::dhcp::PgSqlConfigBackendDHCPv6::unregisterBackendType();
+    }
+
+    /// @brief Method which returns the back end specific connection
+    /// string
+    virtual std::string validConnectString() {
+        return (validPgSQLConnectionString());
+    }
+
+    /// @brief Method which returns invalid back end specific connection
+    /// string
+    virtual std::string invalidConnectString() {
+        return (connectionString(PGSQL_VALID_TYPE, INVALID_NAME, VALID_HOST,
+                                 VALID_USER, VALID_PASSWORD));
+    }
+
+    /// @brief Verifies open failures do NOT invoke db lost callback
+    ///
+    /// The db lost callback should only be invoked after successfully
+    /// opening the DB and then subsequently losing it. Failing to
+    /// open should be handled directly by the application layer.
+    void testNoCallbackOnOpenFailure();
+
+    /// @brief Verifies the CB manager's behavior if DB connection is lost
+    ///
+    /// This function creates a CB manager with a back end that supports
+    /// connectivity lost callback. It verifies connectivity by issuing a known
+    /// valid query. Next it simulates connectivity lost by identifying and
+    /// closing the socket connection to the CB backend. It then reissues the
+    /// query and verifies that:
+    /// -# The Query throws  DbOperationError (rather than exiting)
+    /// -# The registered DbLostCallback was invoked
+    /// -# The registered DbRecoveredCallback was invoked
+    void testDbLostAndRecoveredCallback();
+
+    /// @brief Verifies the CB manager's behavior if DB connection is lost
+    ///
+    /// This function creates a CB manager with a back end that supports
+    /// connectivity lost callback. It verifies connectivity by issuing a known
+    /// valid query. Next it simulates connectivity lost by identifying and
+    /// closing the socket connection to the CB backend. It then reissues the
+    /// query and verifies that:
+    /// -# The Query throws  DbOperationError (rather than exiting)
+    /// -# The registered DbLostCallback was invoked
+    /// -# The registered DbFailedCallback was invoked
+    void testDbLostAndFailedCallback();
+
+    /// @brief Verifies the CB manager's behavior if DB connection is lost
+    ///
+    /// This function creates a CB manager with a back end that supports
+    /// connectivity lost callback. It verifies connectivity by issuing a known
+    /// valid query. Next it simulates connectivity lost by identifying and
+    /// closing the socket connection to the CB backend. It then reissues the
+    /// query and verifies that:
+    /// -# The Query throws  DbOperationError (rather than exiting)
+    /// -# The registered DbLostCallback was invoked
+    /// -# The registered DbRecoveredCallback was invoked after two reconnect
+    /// attempts (once failing and second triggered by timer)
+    void testDbLostAndRecoveredAfterTimeoutCallback();
+
+    /// @brief Verifies the CB manager's behavior if DB connection is lost
+    ///
+    /// This function creates a CB manager with a back end that supports
+    /// connectivity lost callback. It verifies connectivity by issuing a known
+    /// valid query. Next it simulates connectivity lost by identifying and
+    /// closing the socket connection to the CB backend. It then reissues the
+    /// query and verifies that:
+    /// -# The Query throws  DbOperationError (rather than exiting)
+    /// -# The registered DbLostCallback was invoked
+    /// -# The registered DbFailedCallback was invoked after two reconnect
+    /// attempts (once failing and second triggered by timer)
+    void testDbLostAndFailedAfterTimeoutCallback();
+
+    /// @brief Callback function registered with the CB manager
+    bool db_lost_callback(db::ReconnectCtlPtr /* not_used */) {
+        return (++db_lost_callback_called_);
+    }
+
+    /// @brief Flag used to detect calls to db_lost_callback function
+    uint32_t db_lost_callback_called_;
+
+    /// @brief Callback function registered with the CB manager
+    bool db_recovered_callback(db::ReconnectCtlPtr /* not_used */) {
+        return (++db_recovered_callback_called_);
+    }
+
+    /// @brief Flag used to detect calls to db_recovered_callback function
+    uint32_t db_recovered_callback_called_;
+
+    /// @brief Callback function registered with the CB manager
+    bool db_failed_callback(db::ReconnectCtlPtr /* not_used */) {
+        return (++db_failed_callback_called_);
+    }
+
+    /// @brief Flag used to detect calls to db_failed_callback function
+    uint32_t db_failed_callback_called_;
+
+    /// The IOService object, used for all ASIO operations.
+    isc::asiolink::IOServicePtr io_service_;
+};
+
+void
+PgSqlConfigBackendDHCPv6DbLostCallbackTest::testNoCallbackOnOpenFailure() {
+    isc::db::DatabaseConnection::db_lost_callback_ =
+        std::bind(&PgSqlConfigBackendDHCPv6DbLostCallbackTest::db_lost_callback, this, ph::_1);
+
+    // Set the connectivity recovered callback.
+    isc::db::DatabaseConnection::db_recovered_callback_ =
+        std::bind(&PgSqlConfigBackendDHCPv6DbLostCallbackTest::db_recovered_callback, this, ph::_1);
+
+    // Set the connectivity failed callback.
+    isc::db::DatabaseConnection::db_failed_callback_ =
+        std::bind(&PgSqlConfigBackendDHCPv6DbLostCallbackTest::db_failed_callback, this, ph::_1);
+
+    std::string access = invalidConnectString();
+
+    // Connect to the CB backend.
+    ASSERT_THROW(ConfigBackendDHCPv6Mgr::instance().addBackend(access), DbOpenError);
+
+    io_service_->poll();
+
+    EXPECT_EQ(0, db_lost_callback_called_);
+    EXPECT_EQ(0, db_recovered_callback_called_);
+    EXPECT_EQ(0, db_failed_callback_called_);
+}
+
+void
+PgSqlConfigBackendDHCPv6DbLostCallbackTest::testDbLostAndRecoveredCallback() {
+    // Set the connectivity lost callback.
+    isc::db::DatabaseConnection::db_lost_callback_ =
+        std::bind(&PgSqlConfigBackendDHCPv6DbLostCallbackTest::db_lost_callback, this, ph::_1);
+
+    // Set the connectivity recovered callback.
+    isc::db::DatabaseConnection::db_recovered_callback_ =
+        std::bind(&PgSqlConfigBackendDHCPv6DbLostCallbackTest::db_recovered_callback, this, ph::_1);
+
+    // Set the connectivity failed callback.
+    isc::db::DatabaseConnection::db_failed_callback_ =
+        std::bind(&PgSqlConfigBackendDHCPv6DbLostCallbackTest::db_failed_callback, this, ph::_1);
+
+    std::string access = validConnectString();
+
+    ConfigControlInfoPtr config_ctl_info(new ConfigControlInfo());
+    config_ctl_info->addConfigDatabase(access);
+    CfgMgr::instance().getCurrentCfg()->setConfigControlInfo(config_ctl_info);
+
+    // Find the most recently opened socket. Our SQL client's socket should
+    // be the next one.
+    int last_open_socket = findLastSocketFd();
+
+    // Fill holes.
+    FillFdHoles holes(last_open_socket);
+
+    // Connect to the CB backend.
+    ASSERT_NO_THROW(ConfigBackendDHCPv6Mgr::instance().addBackend(access));
+
+    // Find the SQL client socket.
+    int sql_socket = findLastSocketFd();
+    ASSERT_TRUE(sql_socket > last_open_socket);
+
+    // Verify we can execute a query.  We don't care about the answer.
+    ServerCollection servers;
+    ASSERT_NO_THROW(servers = ConfigBackendDHCPv6Mgr::instance().getPool()->getAllServers6(BackendSelector()));
+
+    // Now close the sql socket out from under backend client
+    ASSERT_EQ(0, close(sql_socket));
+
+    // A query should fail with DbConnectionUnusable.
+    ASSERT_THROW(servers = ConfigBackendDHCPv6Mgr::instance().getPool()->getAllServers6(BackendSelector()),
+                 DbConnectionUnusable);
+
+    io_service_->poll();
+
+    // Our lost and recovered connectivity callback should have been invoked.
+    EXPECT_EQ(1, db_lost_callback_called_);
+    EXPECT_EQ(1, db_recovered_callback_called_);
+    EXPECT_EQ(0, db_failed_callback_called_);
+}
+
+void
+PgSqlConfigBackendDHCPv6DbLostCallbackTest::testDbLostAndFailedCallback() {
+    // Set the connectivity lost callback.
+    isc::db::DatabaseConnection::db_lost_callback_ =
+        std::bind(&PgSqlConfigBackendDHCPv6DbLostCallbackTest::db_lost_callback, this, ph::_1);
+
+    // Set the connectivity recovered callback.
+    isc::db::DatabaseConnection::db_recovered_callback_ =
+        std::bind(&PgSqlConfigBackendDHCPv6DbLostCallbackTest::db_recovered_callback, this, ph::_1);
+
+    // Set the connectivity failed callback.
+    isc::db::DatabaseConnection::db_failed_callback_ =
+        std::bind(&PgSqlConfigBackendDHCPv6DbLostCallbackTest::db_failed_callback, this, ph::_1);
+
+    std::string access = validConnectString();
+    ConfigControlInfoPtr config_ctl_info(new ConfigControlInfo());
+    config_ctl_info->addConfigDatabase(access);
+    CfgMgr::instance().getCurrentCfg()->setConfigControlInfo(config_ctl_info);
+
+    // Find the most recently opened socket. Our SQL client's socket should
+    // be the next one.
+    int last_open_socket = findLastSocketFd();
+
+    // Fill holes.
+    FillFdHoles holes(last_open_socket);
+
+    // Connect to the CB backend.
+    ASSERT_NO_THROW(ConfigBackendDHCPv6Mgr::instance().addBackend(access));
+
+    // Find the SQL client socket.
+    int sql_socket = findLastSocketFd();
+    ASSERT_TRUE(sql_socket > last_open_socket);
+
+    // Verify we can execute a query.  We don't care about the answer.
+    ServerCollection servers;
+    ASSERT_NO_THROW(servers = ConfigBackendDHCPv6Mgr::instance().getPool()->getAllServers6(BackendSelector()));
+
+    access = invalidConnectString();
+    CfgMgr::instance().clear();
+    // by adding an invalid access will cause the manager factory to throw
+    // resulting in failure to recreate the manager
+    config_ctl_info.reset(new ConfigControlInfo());
+    config_ctl_info->addConfigDatabase(access);
+    CfgMgr::instance().getCurrentCfg()->setConfigControlInfo(config_ctl_info);
+    const ConfigDbInfoList& cfg = CfgMgr::instance().getCurrentCfg()->getConfigControlInfo()->getConfigDatabases();
+    (const_cast<ConfigDbInfoList&>(cfg))[0].setAccessString(access, true);
+
+    // Now close the sql socket out from under backend client
+    ASSERT_EQ(0, close(sql_socket));
+
+    // A query should fail with DbConnectionUnusable.
+    ASSERT_THROW(servers = ConfigBackendDHCPv6Mgr::instance().getPool()->getAllServers6(BackendSelector()),
+                 DbConnectionUnusable);
+
+    io_service_->poll();
+
+    // Our lost and failed connectivity callback should have been invoked.
+    EXPECT_EQ(1, db_lost_callback_called_);
+    EXPECT_EQ(0, db_recovered_callback_called_);
+    EXPECT_EQ(1, db_failed_callback_called_);
+}
+
+void
+PgSqlConfigBackendDHCPv6DbLostCallbackTest::testDbLostAndRecoveredAfterTimeoutCallback() {
+    // Set the connectivity lost callback.
+    isc::db::DatabaseConnection::db_lost_callback_ =
+        std::bind(&PgSqlConfigBackendDHCPv6DbLostCallbackTest::db_lost_callback, this, ph::_1);
+
+    // Set the connectivity recovered callback.
+    isc::db::DatabaseConnection::db_recovered_callback_ =
+        std::bind(&PgSqlConfigBackendDHCPv6DbLostCallbackTest::db_recovered_callback, this, ph::_1);
+
+    // Set the connectivity failed callback.
+    isc::db::DatabaseConnection::db_failed_callback_ =
+        std::bind(&PgSqlConfigBackendDHCPv6DbLostCallbackTest::db_failed_callback, this, ph::_1);
+
+    std::string access = validConnectString();
+    std::string extra = " max-reconnect-tries=3 reconnect-wait-time=1";
+    access += extra;
+    ConfigControlInfoPtr config_ctl_info(new ConfigControlInfo());
+    config_ctl_info->addConfigDatabase(access);
+    CfgMgr::instance().getCurrentCfg()->setConfigControlInfo(config_ctl_info);
+
+    // Find the most recently opened socket. Our SQL client's socket should
+    // be the next one.
+    int last_open_socket = findLastSocketFd();
+
+    // Fill holes.
+    FillFdHoles holes(last_open_socket);
+
+    // Connect to the CB backend.
+    ASSERT_NO_THROW(ConfigBackendDHCPv6Mgr::instance().addBackend(access));
+
+    // Find the SQL client socket.
+    int sql_socket = findLastSocketFd();
+    ASSERT_TRUE(sql_socket > last_open_socket);
+
+    // Verify we can execute a query.  We don't care about the answer.
+    ServerCollection servers;
+    ASSERT_NO_THROW(servers = ConfigBackendDHCPv6Mgr::instance().getPool()->getAllServers6(BackendSelector()));
+
+    access = invalidConnectString();
+    access += extra;
+    CfgMgr::instance().clear();
+    // by adding an invalid access will cause the manager factory to throw
+    // resulting in failure to recreate the manager
+    config_ctl_info.reset(new ConfigControlInfo());
+    config_ctl_info->addConfigDatabase(access);
+    CfgMgr::instance().getCurrentCfg()->setConfigControlInfo(config_ctl_info);
+    const ConfigDbInfoList& cfg = CfgMgr::instance().getCurrentCfg()->getConfigControlInfo()->getConfigDatabases();
+    (const_cast<ConfigDbInfoList&>(cfg))[0].setAccessString(access, true);
+
+    // Now close the sql socket out from under backend client
+    ASSERT_EQ(0, close(sql_socket));
+
+    // A query should fail with DbConnectionUnusable.
+    ASSERT_THROW(servers = ConfigBackendDHCPv6Mgr::instance().getPool()->getAllServers6(BackendSelector()),
+                 DbConnectionUnusable);
+
+    io_service_->poll();
+
+    // Our lost connectivity callback should have been invoked.
+    EXPECT_EQ(1, db_lost_callback_called_);
+    EXPECT_EQ(0, db_recovered_callback_called_);
+    EXPECT_EQ(0, db_failed_callback_called_);
+
+    access = validConnectString();
+    access += extra;
+    CfgMgr::instance().clear();
+    config_ctl_info.reset(new ConfigControlInfo());
+    config_ctl_info->addConfigDatabase(access);
+    CfgMgr::instance().getCurrentCfg()->setConfigControlInfo(config_ctl_info);
+
+    sleep(1);
+
+    io_service_->poll();
+
+    // Our lost and recovered connectivity callback should have been invoked.
+    EXPECT_EQ(2, db_lost_callback_called_);
+    EXPECT_EQ(1, db_recovered_callback_called_);
+    EXPECT_EQ(0, db_failed_callback_called_);
+
+    sleep(1);
+
+    io_service_->poll();
+
+    // No callback should have been invoked.
+    EXPECT_EQ(2, db_lost_callback_called_);
+    EXPECT_EQ(1, db_recovered_callback_called_);
+    EXPECT_EQ(0, db_failed_callback_called_);
+}
+
+void
+PgSqlConfigBackendDHCPv6DbLostCallbackTest::testDbLostAndFailedAfterTimeoutCallback() {
+    // Set the connectivity lost callback.
+    isc::db::DatabaseConnection::db_lost_callback_ =
+        std::bind(&PgSqlConfigBackendDHCPv6DbLostCallbackTest::db_lost_callback, this, ph::_1);
+
+    // Set the connectivity recovered callback.
+    isc::db::DatabaseConnection::db_recovered_callback_ =
+        std::bind(&PgSqlConfigBackendDHCPv6DbLostCallbackTest::db_recovered_callback, this, ph::_1);
+
+    // Set the connectivity failed callback.
+    isc::db::DatabaseConnection::db_failed_callback_ =
+        std::bind(&PgSqlConfigBackendDHCPv6DbLostCallbackTest::db_failed_callback, this, ph::_1);
+
+    std::string access = validConnectString();
+    std::string extra = " max-reconnect-tries=3 reconnect-wait-time=1";
+    access += extra;
+    ConfigControlInfoPtr config_ctl_info(new ConfigControlInfo());
+    config_ctl_info->addConfigDatabase(access);
+    CfgMgr::instance().getCurrentCfg()->setConfigControlInfo(config_ctl_info);
+
+    // Find the most recently opened socket. Our SQL client's socket should
+    // be the next one.
+    int last_open_socket = findLastSocketFd();
+
+    // Fill holes.
+    FillFdHoles holes(last_open_socket);
+
+    // Connect to the CB backend.
+    ASSERT_NO_THROW(ConfigBackendDHCPv6Mgr::instance().addBackend(access));
+
+    // Find the SQL client socket.
+    int sql_socket = findLastSocketFd();
+    ASSERT_TRUE(sql_socket > last_open_socket);
+
+    // Verify we can execute a query.  We don't care about the answer.
+    ServerCollection servers;
+    ASSERT_NO_THROW(servers = ConfigBackendDHCPv6Mgr::instance().getPool()->getAllServers6(BackendSelector()));
+
+    access = invalidConnectString();
+    access += extra;
+    CfgMgr::instance().clear();
+    // by adding an invalid access will cause the manager factory to throw
+    // resulting in failure to recreate the manager
+    config_ctl_info.reset(new ConfigControlInfo());
+    config_ctl_info->addConfigDatabase(access);
+    CfgMgr::instance().getCurrentCfg()->setConfigControlInfo(config_ctl_info);
+    const ConfigDbInfoList& cfg = CfgMgr::instance().getCurrentCfg()->getConfigControlInfo()->getConfigDatabases();
+    (const_cast<ConfigDbInfoList&>(cfg))[0].setAccessString(access, true);
+
+    // Now close the sql socket out from under backend client
+    ASSERT_EQ(0, close(sql_socket));
+
+    // A query should fail with DbConnectionUnusable.
+    ASSERT_THROW(servers = ConfigBackendDHCPv6Mgr::instance().getPool()->getAllServers6(BackendSelector()),
+                 DbConnectionUnusable);
+
+    io_service_->poll();
+
+    // Our lost connectivity callback should have been invoked.
+    EXPECT_EQ(1, db_lost_callback_called_);
+    EXPECT_EQ(0, db_recovered_callback_called_);
+    EXPECT_EQ(0, db_failed_callback_called_);
+
+    sleep(1);
+
+    io_service_->poll();
+
+    // Our lost connectivity callback should have been invoked.
+    EXPECT_EQ(2, db_lost_callback_called_);
+    EXPECT_EQ(0, db_recovered_callback_called_);
+    EXPECT_EQ(0, db_failed_callback_called_);
+
+    sleep(1);
+
+    io_service_->poll();
+
+    // Our lost and failed connectivity callback should have been invoked.
+    EXPECT_EQ(3, db_lost_callback_called_);
+    EXPECT_EQ(0, db_recovered_callback_called_);
+    EXPECT_EQ(1, db_failed_callback_called_);
+}
+
+/// @brief Verifies that db lost callback is not invoked on an open failure
+TEST_F(PgSqlConfigBackendDHCPv6DbLostCallbackTest, testNoCallbackOnOpenFailure) {
+    MultiThreadingTest mt(false);
+    testNoCallbackOnOpenFailure();
+}
+
+/// @brief Verifies that db lost callback is not invoked on an open failure
+TEST_F(PgSqlConfigBackendDHCPv6DbLostCallbackTest, testNoCallbackOnOpenFailureMultiThreading) {
+    MultiThreadingTest mt(true);
+    testNoCallbackOnOpenFailure();
+}
+
+/// @brief Verifies that loss of connectivity to Postgres is handled correctly.
+TEST_F(PgSqlConfigBackendDHCPv6DbLostCallbackTest, testDbLostAndRecoveredCallback) {
+    MultiThreadingTest mt(false);
+    testDbLostAndRecoveredCallback();
+}
+
+/// @brief Verifies that loss of connectivity to Postgres is handled correctly.
+TEST_F(PgSqlConfigBackendDHCPv6DbLostCallbackTest, testDbLostAndRecoveredCallbackMultiThreading) {
+    MultiThreadingTest mt(true);
+    testDbLostAndRecoveredCallback();
+}
+
+/// @brief Verifies that loss of connectivity to Postgres is handled correctly.
+TEST_F(PgSqlConfigBackendDHCPv6DbLostCallbackTest, testDbLostAndFailedCallback) {
+    MultiThreadingTest mt(false);
+    testDbLostAndFailedCallback();
+}
+
+/// @brief Verifies that loss of connectivity to Postgres is handled correctly.
+TEST_F(PgSqlConfigBackendDHCPv6DbLostCallbackTest, testDbLostAndFailedCallbackMultiThreading) {
+    MultiThreadingTest mt(true);
+    testDbLostAndFailedCallback();
+}
+
+/// @brief Verifies that loss of connectivity to Postgres is handled correctly.
+TEST_F(PgSqlConfigBackendDHCPv6DbLostCallbackTest, testDbLostAndRecoveredAfterTimeoutCallback) {
+    MultiThreadingTest mt(false);
+    testDbLostAndRecoveredAfterTimeoutCallback();
+}
+
+/// @brief Verifies that loss of connectivity to Postgres is handled correctly.
+TEST_F(PgSqlConfigBackendDHCPv6DbLostCallbackTest, testDbLostAndRecoveredAfterTimeoutCallbackMultiThreading) {
+    MultiThreadingTest mt(true);
+    testDbLostAndRecoveredAfterTimeoutCallback();
+}
+
+/// @brief Verifies that loss of connectivity to Postgres is handled correctly.
+TEST_F(PgSqlConfigBackendDHCPv6DbLostCallbackTest, testDbLostAndFailedAfterTimeoutCallback) {
+    MultiThreadingTest mt(false);
+    testDbLostAndFailedAfterTimeoutCallback();
+}
+
+/// @brief Verifies that loss of connectivity to Postgres is handled correctly.
+TEST_F(PgSqlConfigBackendDHCPv6DbLostCallbackTest, testDbLostAndFailedAfterTimeoutCallbackMultiThreading) {
+    MultiThreadingTest mt(true);
+    testDbLostAndFailedAfterTimeoutCallback();
+}
+
+}