Function registerDatabaseReplicated

src/Databases/DatabaseReplicated.cpp:2627–2879

void registerDatabaseReplicated(DatabaseFactory & factory);
void registerDatabaseReplicated(DatabaseFactory & factory)
{
    auto create_fn = [](const DatabaseFactory::Arguments & args)
    {
        auto * engine_define = args.create_query.storage;
        ASTFunction * engine = engine_define->engine;

        /// Fill in default parameters
        if (!args.create_query.attach)
        {
            if (!engine->arguments)
            {
                engine->arguments = make_intrusive<ASTExpressionList>();
                engine->children.push_back(engine->arguments);
            }

            auto settings = args.context->getDatabaseReplicatedSettings();
            if (engine->arguments->children.empty())
                engine->arguments->children.emplace_back(make_intrusive<ASTLiteral>(settings[DatabaseReplicatedSetting::default_replica_path].value));
            if (engine->arguments->children.size() == 1)
                engine->arguments->children.emplace_back(make_intrusive<ASTLiteral>(settings[DatabaseReplicatedSetting::default_replica_shard_name].value));
            if (engine->arguments->children.size() == 2)
                engine->arguments->children.emplace_back(make_intrusive<ASTLiteral>(settings[DatabaseReplicatedSetting::default_replica_name].value));
        }

        if (!engine->arguments || engine->arguments->children.size() != 3)
            throw Exception(ErrorCodes::BAD_ARGUMENTS, "Replicated database requires 3 arguments: zookeeper path, shard name and replica name");

        auto & arguments = engine->arguments->children;
        for (auto & engine_arg : arguments)
            engine_arg = evaluateConstantExpressionOrIdentifierAsLiteral(engine_arg, args.context);

        String zookeeper_path = safeGetLiteralValue<String>(arguments[0], "Replicated");
        String shard_name = safeGetLiteralValue<String>(arguments[1], "Replicated");
        String replica_name  = safeGetLiteralValue<String>(arguments[2], "Replicated");

        /// Expand macros.
        Macros::MacroExpansionInfo info;
        info.expand_for_database = true;
        info.table_id.database_name = args.database_name;

        const bool is_on_cluster = args.context->isDDLOrOnClusterInternal();
        /// Allow implicit {uuid} macros only for zookeeper_path in ON CLUSTER queries
        /// and if UUID was explicitly passed in CREATE DATABASE (like for ATTACH)
        bool allow_uuid_macro = is_on_cluster || args.create_query.attach || args.create_query.has_uuid;
        if (allow_uuid_macro)
            info.table_id.uuid = args.uuid;
        zookeeper_path = args.context->getMacros()->expand(zookeeper_path, info);
        auto zookeeper_name = zkutil::extractZooKeeperName(zookeeper_path);
        zookeeper_path = zkutil::extractZooKeeperPath(zookeeper_path, /*check_starts_with_slash*/false);

        info.level = 0;
        info.table_id.uuid = UUIDHelpers::Nil;
        shard_name = args.context->getMacros()->expand(shard_name, info);

        info.level = 0;
        replica_name = args.context->getMacros()->expand(replica_name, info);