Function registerStorageFile

src/Storages/StorageFile.cpp:723–833

void registerStorageFile(StorageFactory & factory)
{
    StorageFactory::StorageFeatures storage_features{
        .supports_settings = true,
        .source_access_type = AccessType::FILE
    };

    factory.registerStorage(
        "File",
        [](const StorageFactory::Arguments & factory_args)
        {
            StorageFile::CommonArguments storage_args
            {
                WithContext(factory_args.getContext()),
                factory_args.table_id,
                {},
                {},
                {},
                factory_args.columns,
                factory_args.constraints,
                factory_args.comment,
            };

            ASTs & engine_args_ast = factory_args.engine_args;

            if (!(engine_args_ast.size() >= 1 && engine_args_ast.size() <= 3)) // NOLINT
                throw Exception(
                    "Storage File requires from 1 to 3 arguments: name of used format, source and compression_method.",
                    ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);

            engine_args_ast[0] = evaluateConstantExpressionOrIdentifierAsLiteral(engine_args_ast[0], factory_args.getLocalContext());
            storage_args.format_name = engine_args_ast[0]->as<ASTLiteral &>().value.safeGet<String>();

            // Use format settings from global server context + settings from
            // the SETTINGS clause of the create query. Settings from current
            // session and user are ignored.
            if (factory_args.storage_def->settings)
            {
                FormatFactorySettings user_format_settings;

                // Apply changed settings from global context, but ignore the
                // unknown ones, because we only have the format settings here.
                const auto & changes = factory_args.getContext()->getSettingsRef().changes();
                for (const auto & change : changes)
                {
                    if (user_format_settings.has(change.name))
                    {
                        user_format_settings.set(change.name, change.value);
                    }
                }

                // Apply changes from SETTINGS clause, with validation.
                user_format_settings.applyChanges(
                    factory_args.storage_def->settings->changes);

                storage_args.format_settings = getFormatSettings(
                    factory_args.getContext(), user_format_settings);
            }