Method comQuery

src/Server/MySQLHandler.cpp:480–578

}

void MySQLHandler::comQuery(ReadBuffer & payload, bool binary_protocol)
{
    String query = String(payload.position(), payload.buffer().end());

    // This is a workaround in order to support adding ClickHouse to MySQL using federated server.
    // As Clickhouse doesn't support these statements, we just send OK packet in response.
    if (isFederatedServerSetupSetCommand(query))
    {
        packet_endpoint->sendPacket(OKPacket(0x00, client_capabilities, 0, 0, 0));
    }
    else
    {
        String replacement_query;
        bool should_replace = false;
        bool with_output = false;

        // Queries replacements
        for (auto const & [query_to_replace, replacement_fn] : queries_replacements)
        {
            if (checkShouldReplaceQuery(query, query_to_replace))
            {
                should_replace = true;
                replacement_query = replacement_fn(query);
                break;
            }
        }

        // Settings replacements
        if (!should_replace)
        {
            for (auto const & [mysql_setting, clickhouse_setting] : settings_replacements)
            {
                const auto replacement_query_opt = setSettingReplacementQuery(query, mysql_setting, clickhouse_setting);
                if (replacement_query_opt.has_value())
                {
                    should_replace = true;
                    replacement_query = replacement_query_opt.value();
                    break;
                }
            }
        }

        auto query_context = session->makeQueryContext();
        query_context->setCurrentQueryId(fmt::format("mysql:{}:{}", connection_id, toString(UUIDHelpers::generateV4())));

        /// --- Workaround for Bug 56173.
        auto settings = query_context->getSettingsCopy();
        if (!settings[Setting::allow_experimental_analyzer])
        {
            settings[Setting::prefer_column_name_to_alias] = true;
            query_context->setSettings(settings);
        }

        /// Update timeouts
        socket().setReceiveTimeout(settings[Setting::receive_timeout]);
        socket().setSendTimeout(settings[Setting::send_timeout]);

        QueryScope query_scope = QueryScope::create(query_context);