Function loadMetadataSystem

src/Interpreters/loadMetadata.cpp:617–654

}

LoadTaskPtrs loadMetadataSystem(ContextMutablePtr context, bool async_load_system_database)
{
    auto component_guard = Coordination::setCurrentComponent("loadMetadataSystem");
    loadSystemDatabaseImpl(context, DatabaseCatalog::SYSTEM_DATABASE,
        context->getApplicationType() == Context::ApplicationType::SERVER ? "Atomic" : "Memory");
    loadSystemDatabaseImpl(context, DatabaseCatalog::INFORMATION_SCHEMA, "Memory");
    loadSystemDatabaseImpl(context, DatabaseCatalog::INFORMATION_SCHEMA_UPPERCASE, "Memory");

    TablesLoader::Databases databases =
    {
        {DatabaseCatalog::SYSTEM_DATABASE, DatabaseCatalog::instance().getSystemDatabase()},
        {DatabaseCatalog::INFORMATION_SCHEMA, DatabaseCatalog::instance().getDatabase(DatabaseCatalog::INFORMATION_SCHEMA)},
        {DatabaseCatalog::INFORMATION_SCHEMA_UPPERCASE, DatabaseCatalog::instance().getDatabase(DatabaseCatalog::INFORMATION_SCHEMA_UPPERCASE)},
    };
    TablesLoader loader{context, databases, LoadingStrictnessLevel::FORCE_RESTORE};

    auto load_tasks = loader.loadTablesAsync();
    auto startup_tasks = loader.startupTablesAsync();

    if (async_load_system_database)
    {
        scheduleLoad(load_tasks);
        scheduleLoad(startup_tasks);

        // Do NOT wait, just return tasks for continuation or later wait.
        return joinTasks(load_tasks, startup_tasks);
    }
    else
    {
        waitLoad(TablesLoaderForegroundPoolId, load_tasks);

        /// This has to be done before the initialization of system logs `initializeSystemLogs()`,
        /// otherwise there is a race condition between the system database initialization
        /// and creation of new tables in the database.
        waitLoad(TablesLoaderForegroundPoolId, startup_tasks);
        return {};
    }
}

}