#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "config_version.h" namespace DB { namespace ErrorCodes { extern const int TOO_DEEP_SUBQUERIES; extern const int SAMPLING_NOT_SUPPORTED; extern const int ILLEGAL_FINAL; extern const int ILLEGAL_PREWHERE; extern const int TOO_MANY_COLUMNS; extern const int LOGICAL_ERROR; extern const int NOT_IMPLEMENTED; extern const int PARAMETER_OUT_OF_BOUND; extern const int INVALID_LIMIT_EXPRESSION; extern const int INVALID_WITH_FILL_EXPRESSION; extern const int ACCESS_DENIED; extern const int UNKNOWN_IDENTIFIER; extern const int BAD_ARGUMENTS; } /// Assumes `storage` is set and the table filter (row-level security) is not empty. FilterDAGInfoPtr generateFilterActions( const StorageID & table_id, const ASTPtr & row_policy_filter_expression, const ContextPtr & context, const StoragePtr & storage, const StorageSnapshotPtr & storage_snapshot, const StorageMetadataPtr & metadata_snapshot, Names & prerequisite_columns, PreparedSetsPtr prepared_sets) { auto filter_info = std::make_shared(); const auto & db_name = table_id.getDatabaseName(); const auto & table_name = table_id.getTableName(); /// TODO: implement some AST builders for this kind of stuff ASTPtr query_ast = std::make_shared(); auto * select_ast = query_ast->as(); select_ast->setExpression(ASTSelectQuery::Expression::SELECT, std::make_shared()); auto expr_list = select_ast->select(); /// The first column is our filter expression. /// the row_policy_filter_expression should be cloned, because it may be changed by TreeRewriter. /// which make it possible an invalid expression, although it may be valid in whole select. expr_list->children.push_back(row_policy_filter_expression->clone()); /// Keep columns that are required after the filter actions. for (const auto & column_str : prerequisite_columns) { ParserExpression expr_parser; /// We should add back quotes around column name as it can contain dots. expr_list->children.push_back(parseQuery(expr_parser, backQuoteIfNeed(column_str), 0, context->getSettingsRef().max_parser_depth)); } select_ast->setExpression(ASTSelectQuery::Expression::TABLES, std::make_shared()); auto tables = select_ast->tables(); auto tables_elem = std::make_shared(); auto table_expr = std::make_shared(); tables->children.push_back(tables_elem); tables_elem->table_expression = table_expr; tables_elem->children.push_back(table_expr); table_expr->database_and_table_name = std::make_shared(db_name, table_name); table_expr->children.push_back(table_expr->database_and_table_name); /// Using separate expression analyzer to prevent any possible alias injection auto syntax_result = TreeRewriter(context).analyzeSelect(query_ast, TreeRewriterResult({}, storage, storage_snapshot)); SelectQueryExpressionAnalyzer analyzer(query_ast, syntax_result, context, metadata_snapshot, {}, false, {}, prepared_sets); filter_info->actions = analyzer.simpleSelectActions(); filter_info->column_name = expr_list->children.at(0)->getColumnName(); filter_info->actions->removeUnusedActions(NameSet{filter_info->column_name}); filter_info->actions->projectInput(false); for (const auto * node : filter_info->actions->getInputs()) filter_info->actions->getOutputs().push_back(node); auto required_columns_from_filter = filter_info->actions->getRequiredColumns(); for (const auto & column : required_columns_from_filter) { if (prerequisite_columns.end() == std::find(prerequisite_columns.begin(), prerequisite_columns.end(), column.name)) prerequisite_columns.push_back(column.name); } return filter_info; } InterpreterSelectQuery::InterpreterSelectQuery( const ASTPtr & query_ptr_, const ContextPtr & context_, const SelectQueryOptions & options_, const Names & required_result_column_names_) : InterpreterSelectQuery(query_ptr_, context_, std::nullopt, nullptr, options_, required_result_column_names_) {} InterpreterSelectQuery::InterpreterSelectQuery( const ASTPtr & query_ptr_, const ContextMutablePtr & context_, const SelectQueryOptions & options_, const Names & required_result_column_names_) : InterpreterSelectQuery(query_ptr_, context_, std::nullopt, nullptr, options_, required_result_column_names_) {} InterpreterSelectQuery::InterpreterSelectQuery( const ASTPtr & query_ptr_, const ContextPtr & context_, Pipe input_pipe_, const SelectQueryOptions & options_) : InterpreterSelectQuery(query_ptr_, context_, std::move(input_pipe_), nullptr, options_.copy().noSubquery()) {} InterpreterSelectQuery::InterpreterSelectQuery( const ASTPtr & query_ptr_, const ContextPtr & context_, const StoragePtr & storage_, const StorageMetadataPtr & metadata_snapshot_, const SelectQueryOptions & options_) : InterpreterSelectQuery(query_ptr_, context_, std::nullopt, storage_, options_.copy().noSubquery(), {}, metadata_snapshot_) {} InterpreterSelectQuery::InterpreterSelectQuery( const ASTPtr & query_ptr_, const ContextPtr & context_, const SelectQueryOptions & options_, PreparedSetsPtr prepared_sets_) : InterpreterSelectQuery( query_ptr_, context_, std::nullopt, nullptr, options_, {}, {}, prepared_sets_) {} InterpreterSelectQuery::~InterpreterSelectQuery() = default; namespace { /** There are no limits on the maximum size of the result for the subquery. * Since the result of the query is not the result of the entire query. */ ContextPtr getSubqueryContext(const ContextPtr & context) { auto subquery_context = Context::createCopy(context); Settings subquery_settings = context->getSettings(); subquery_settings.max_result_rows = 0; subquery_settings.max_result_bytes = 0; /// The calculation of extremes does not make sense and is not necessary (if you do it, then the extremes of the subquery can be taken for whole query). subquery_settings.extremes = false; subquery_context->setSettings(subquery_settings); return subquery_context; } void rewriteMultipleJoins(ASTPtr & query, const TablesWithColumns & tables, const String & database, const Settings & settings) { ASTSelectQuery & select = query->as(); Aliases aliases; if (ASTPtr with = select.with()) QueryAliasesNoSubqueriesVisitor(aliases).visit(with); QueryAliasesNoSubqueriesVisitor(aliases).visit(select.select()); CrossToInnerJoinVisitor::Data cross_to_inner{tables, aliases, database}; cross_to_inner.cross_to_inner_join_rewrite = static_cast(std::min(settings.cross_to_inner_join_rewrite, 2)); CrossToInnerJoinVisitor(cross_to_inner).visit(query); JoinToSubqueryTransformVisitor::Data join_to_subs_data{tables, aliases}; join_to_subs_data.try_to_keep_original_names = settings.multiple_joins_try_to_keep_original_names; JoinToSubqueryTransformVisitor(join_to_subs_data).visit(query); } /// Checks that the current user has the SELECT privilege. void checkAccessRightsForSelect( const ContextPtr & context, const StorageID & table_id, const StorageMetadataPtr & table_metadata, const TreeRewriterResult & syntax_analyzer_result) { if (!syntax_analyzer_result.has_explicit_columns && table_metadata && !table_metadata->getColumns().empty()) { /// For a trivial query like "SELECT count() FROM table" access is granted if at least /// one column is accessible. /// In this case just checking access for `required_columns` doesn't work correctly /// because `required_columns` will contain the name of a column of minimum size (see TreeRewriterResult::collectUsedColumns()) /// which is probably not the same column as the column the current user has access to. auto access = context->getAccess(); for (const auto & column : table_metadata->getColumns()) { if (access->isGranted(AccessType::SELECT, table_id.database_name, table_id.table_name, column.name)) return; } throw Exception( ErrorCodes::ACCESS_DENIED, "{}: Not enough privileges. To execute this query it's necessary to have grant SELECT for at least one column on {}", context->getUserName(), table_id.getFullTableName()); } /// General check. context->checkAccess(AccessType::SELECT, table_id, syntax_analyzer_result.requiredSourceColumnsForAccessCheck()); } ASTPtr parseAdditionalFilterConditionForTable( const Map & additional_table_filters, const DatabaseAndTableWithAlias & target, const Context & context) { for (const auto & additional_filter : additional_table_filters) { const auto & tuple = additional_filter.safeGet(); auto & table = tuple.at(0).safeGet(); auto & filter = tuple.at(1).safeGet(); if (table == target.alias || (table == target.table && context.getCurrentDatabase() == target.database) || (table == target.database + '.' + target.table)) { /// Try to parse expression ParserExpression parser; const auto & settings = context.getSettingsRef(); return parseQuery( parser, filter.data(), filter.data() + filter.size(), "additional filter", settings.max_query_size, settings.max_parser_depth); } } return nullptr; } /// Returns true if we should ignore quotas and limits for a specified table in the system database. bool shouldIgnoreQuotaAndLimits(const StorageID & table_id) { if (table_id.database_name == DatabaseCatalog::SYSTEM_DATABASE) { static const boost::container::flat_set tables_ignoring_quota{"quotas", "quota_limits", "quota_usage", "quotas_usage", "one"}; if (tables_ignoring_quota.count(table_id.table_name)) return true; } return false; } } InterpreterSelectQuery::InterpreterSelectQuery( const ASTPtr & query_ptr_, const ContextPtr & context_, std::optional input_pipe_, const StoragePtr & storage_, const SelectQueryOptions & options_, const Names & required_result_column_names, const StorageMetadataPtr & metadata_snapshot_, PreparedSetsPtr prepared_sets_) : InterpreterSelectQuery( query_ptr_, Context::createCopy(context_), std::move(input_pipe_), storage_, options_, required_result_column_names, metadata_snapshot_, prepared_sets_) {} InterpreterSelectQuery::InterpreterSelectQuery( const ASTPtr & query_ptr_, const ContextMutablePtr & context_, std::optional input_pipe_, const StoragePtr & storage_, const SelectQueryOptions & options_, const Names & required_result_column_names, const StorageMetadataPtr & metadata_snapshot_, PreparedSetsPtr prepared_sets_) /// NOTE: the query almost always should be cloned because it will be modified during analysis. : IInterpreterUnionOrSelectQuery(options_.modify_inplace ? query_ptr_ : query_ptr_->clone(), context_, options_) , storage(storage_) , input_pipe(std::move(input_pipe_)) , log(&Poco::Logger::get("InterpreterSelectQuery")) , metadata_snapshot(metadata_snapshot_) , prepared_sets(prepared_sets_) { checkStackSize(); if (!prepared_sets) prepared_sets = std::make_shared(); query_info.ignore_projections = options.ignore_projections; query_info.is_projection_query = options.is_projection_query; initSettings(); const Settings & settings = context->getSettingsRef(); if (settings.max_subquery_depth && options.subquery_depth > settings.max_subquery_depth) throw Exception(ErrorCodes::TOO_DEEP_SUBQUERIES, "Too deep subqueries. Maximum: {}", settings.max_subquery_depth.toString()); bool has_input = input_pipe != std::nullopt; if (input_pipe) { /// Read from prepared input. source_header = input_pipe->getHeader(); } // Only propagate WITH elements to subqueries if we're not a subquery if (!options.is_subquery) { if (context->getSettingsRef().enable_global_with_statement) ApplyWithAliasVisitor().visit(query_ptr); ApplyWithSubqueryVisitor().visit(query_ptr); } query_info.original_query = query_ptr->clone(); if (settings.count_distinct_optimization) { RewriteCountDistinctFunctionMatcher::Data data_rewrite_countdistinct; RewriteCountDistinctFunctionVisitor(data_rewrite_countdistinct).visit(query_ptr); } JoinedTables joined_tables(getSubqueryContext(context), getSelectQuery(), options.with_all_cols, options_.is_create_parameterized_view); bool got_storage_from_query = false; if (!has_input && !storage) { storage = joined_tables.getLeftTableStorage(); // Mark uses_view_source if the returned storage is the same as the one saved in viewSource uses_view_source |= storage && storage == context->getViewSource(); got_storage_from_query = true; } if (storage) { table_lock = storage->lockForShare(context->getInitialQueryId(), context->getSettingsRef().lock_acquire_timeout); table_id = storage->getStorageID(); if (!metadata_snapshot) metadata_snapshot = storage->getInMemoryMetadataPtr(); storage_snapshot = storage->getStorageSnapshotForQuery(metadata_snapshot, query_ptr, context); } if (has_input || !joined_tables.resolveTables()) joined_tables.makeFakeTable(storage, metadata_snapshot, source_header); if (context->getCurrentTransaction() && context->getSettingsRef().throw_on_unsupported_query_inside_transaction) { if (storage) checkStorageSupportsTransactionsIfNeeded(storage, context, /* is_readonly_query */ true); for (const auto & table : joined_tables.tablesWithColumns()) { if (table.table.table.empty()) continue; auto maybe_storage = DatabaseCatalog::instance().tryGetTable({table.table.database, table.table.table}, context); if (!maybe_storage) continue; checkStorageSupportsTransactionsIfNeeded(storage, context, /* is_readonly_query */ true); } } if (joined_tables.tablesCount() > 1 && (!settings.parallel_replicas_custom_key.value.empty() || settings.allow_experimental_parallel_reading_from_replicas)) { LOG_WARNING(log, "Joins are not supported with parallel replicas. Query will be executed without using them."); context->setSetting("allow_experimental_parallel_reading_from_replicas", false); context->setSetting("parallel_replicas_custom_key", String{""}); } /// Try to execute query without parallel replicas if we find that there is a FINAL modifier there. bool is_query_with_final = false; if (query_info.table_expression_modifiers) is_query_with_final = query_info.table_expression_modifiers->hasFinal(); else if (query_info.query) is_query_with_final = query_info.query->as().final(); if (is_query_with_final && (!settings.parallel_replicas_custom_key.value.empty() || settings.allow_experimental_parallel_reading_from_replicas)) { LOG_WARNING(log, "FINAL modifier is supported with parallel replicas. Will try to execute the query without using them."); context->setSetting("allow_experimental_parallel_reading_from_replicas", false); context->setSetting("parallel_replicas_custom_key", String{""}); } /// Rewrite JOINs if (!has_input && joined_tables.tablesCount() > 1) { rewriteMultipleJoins(query_ptr, joined_tables.tablesWithColumns(), context->getCurrentDatabase(), context->getSettingsRef()); joined_tables.reset(getSelectQuery()); joined_tables.resolveTables(); if (auto view_source = context->getViewSource()) { // If we are using a virtual block view to replace a table and that table is used // inside the JOIN then we need to update uses_view_source accordingly so we avoid propagating scalars that we can't cache const auto & storage_values = static_cast(*view_source); auto tmp_table_id = storage_values.getStorageID(); for (const auto & t : joined_tables.tablesWithColumns()) uses_view_source |= (t.table.database == tmp_table_id.database_name && t.table.table == tmp_table_id.table_name); } if (storage && joined_tables.isLeftTableSubquery()) { /// Rewritten with subquery. Free storage locks here. storage = nullptr; table_lock.reset(); table_id = StorageID::createEmpty(); metadata_snapshot = nullptr; storage_snapshot = nullptr; } } if (!has_input) { interpreter_subquery = joined_tables.makeLeftTableSubquery(options.subquery()); if (interpreter_subquery) { source_header = interpreter_subquery->getSampleBlock(); uses_view_source |= interpreter_subquery->usesViewSource(); } } joined_tables.rewriteDistributedInAndJoins(query_ptr); max_streams = settings.max_threads; ASTSelectQuery & query = getSelectQuery(); std::shared_ptr table_join = joined_tables.makeTableJoin(query); if (storage) row_policy_filter = context->getRowPolicyFilter(table_id.getDatabaseName(), table_id.getTableName(), RowPolicyFilterType::SELECT_FILTER); StorageView * view = nullptr; if (storage) view = dynamic_cast(storage.get()); if (!settings.additional_table_filters.value.empty() && storage && !joined_tables.tablesWithColumns().empty()) query_info.additional_filter_ast = parseAdditionalFilterConditionForTable( settings.additional_table_filters, joined_tables.tablesWithColumns().front().table, *context); ASTPtr parallel_replicas_custom_filter_ast = nullptr; if (storage && context->getParallelReplicasMode() == Context::ParallelReplicasMode::CUSTOM_KEY && !joined_tables.tablesWithColumns().empty()) { if (settings.parallel_replicas_count > 1) { if (auto custom_key_ast = parseCustomKeyForTable(settings.parallel_replicas_custom_key, *context)) { LOG_TRACE(log, "Processing query on a replica using custom_key '{}'", settings.parallel_replicas_custom_key.value); parallel_replicas_custom_filter_ast = getCustomKeyFilterForParallelReplica( settings.parallel_replicas_count, settings.parallel_replica_offset, std::move(custom_key_ast), settings.parallel_replicas_custom_key_filter_type, *storage, context); } else if (settings.parallel_replica_offset > 0) { throw Exception( ErrorCodes::BAD_ARGUMENTS, "Parallel replicas processing with custom_key has been requested " "(setting 'max_parallel_replicas') but the table does not have custom_key defined for it " "or it's invalid (settings `parallel_replicas_custom_key`)"); } } else if (auto * distributed = dynamic_cast(storage.get()); distributed && canUseCustomKey(settings, *distributed->getCluster(), *context)) { query_info.use_custom_key = true; context->setSetting("distributed_group_by_no_merge", 2); } } if (autoFinalOnQuery(query)) { query.setFinal(); } auto analyze = [&] (bool try_move_to_prewhere) { /// Allow push down and other optimizations for VIEW: replace with subquery and rewrite it. ASTPtr view_table; NameToNameMap parameter_types; if (view) { query_info.is_parameterized_view = view->isParameterizedView(); /// We need to fetch the parameters set for SELECT ... FROM parameterized_view() before the query is replaced. /// replaceWithSubquery replaces the function child and adds the subquery in its place. /// the parameters are children of function child, if function (which corresponds to parametrised view and has /// parameters in its arguments: `parametrised_view()`) is replaced the parameters are also gone from tree /// So we need to get the parameters before they are removed from the tree /// and after query is replaced, we use these parameters to substitute in the parameterized view query if (query_info.is_parameterized_view) { query_info.parameterized_view_values = analyzeFunctionParamValues(query_ptr); parameter_types = view->getParameterTypes(); } view->replaceWithSubquery(getSelectQuery(), view_table, metadata_snapshot, view->isParameterizedView()); if (query_info.is_parameterized_view) { view->replaceQueryParametersIfParametrizedView(query_ptr, query_info.parameterized_view_values); } } syntax_analyzer_result = TreeRewriter(context).analyzeSelect( query_ptr, TreeRewriterResult(source_header.getNamesAndTypesList(), storage, storage_snapshot), options, joined_tables.tablesWithColumns(), required_result_column_names, table_join, query_info.is_parameterized_view, query_info.parameterized_view_values, parameter_types); query_info.syntax_analyzer_result = syntax_analyzer_result; context->setDistributed(syntax_analyzer_result->is_remote_storage); if (storage && !query.final() && storage->needRewriteQueryWithFinal(syntax_analyzer_result->requiredSourceColumns())) query.setFinal(); /// Save scalar sub queries's results in the query context /// Note that we are only saving scalars and not local_scalars since the latter can't be safely shared across contexts if (!options.only_analyze && context->hasQueryContext()) for (const auto & it : syntax_analyzer_result->getScalars()) context->getQueryContext()->addScalar(it.first, it.second); if (view) { /// Restore original view name. Save rewritten subquery for future usage in StorageView. query_info.view_query = view->restoreViewName(getSelectQuery(), view_table); view = nullptr; } if (try_move_to_prewhere && storage && storage->canMoveConditionsToPrewhere() && query.where() && !query.prewhere() && !query.hasJoin()) /// Join may produce rows with nulls or default values, it's difficult to analyze if they affected or not. { /// PREWHERE optimization: transfer some condition from WHERE to PREWHERE if enabled and viable if (const auto & column_sizes = storage->getColumnSizes(); !column_sizes.empty()) { /// Extract column compressed sizes. std::unordered_map column_compressed_sizes; for (const auto & [name, sizes] : column_sizes) column_compressed_sizes[name] = sizes.data_compressed; SelectQueryInfo current_info; current_info.query = query_ptr; current_info.syntax_analyzer_result = syntax_analyzer_result; Names queried_columns = syntax_analyzer_result->requiredSourceColumns(); const auto & supported_prewhere_columns = storage->supportedPrewhereColumns(); MergeTreeWhereOptimizer where_optimizer{ std::move(column_compressed_sizes), metadata_snapshot, queried_columns, supported_prewhere_columns, log}; where_optimizer.optimize(current_info, context); } } if (query.prewhere() && query.where()) { /// Filter block in WHERE instead to get better performance query.setExpression( ASTSelectQuery::Expression::WHERE, makeASTFunction("and", query.prewhere()->clone(), query.where()->clone())); } query_analyzer = std::make_unique( query_ptr, syntax_analyzer_result, context, metadata_snapshot, required_result_column_names, !options.only_analyze, options, prepared_sets); if (!options.only_analyze) { if (query.sampleSize() && (input_pipe || !storage || !storage->supportsSampling())) throw Exception(ErrorCodes::SAMPLING_NOT_SUPPORTED, "Illegal SAMPLE: table doesn't support sampling"); if (query.final() && (input_pipe || !storage || !storage->supportsFinal())) { if (!input_pipe && storage) throw Exception(ErrorCodes::ILLEGAL_FINAL, "Storage {} doesn't support FINAL", storage->getName()); else throw Exception(ErrorCodes::ILLEGAL_FINAL, "Illegal FINAL"); } if (query.prewhere() && (input_pipe || !storage || !storage->supportsPrewhere())) { if (!input_pipe && storage) throw Exception(ErrorCodes::ILLEGAL_PREWHERE, "Storage {} doesn't support PREWHERE", storage->getName()); else throw Exception(ErrorCodes::ILLEGAL_PREWHERE, "Illegal PREWHERE"); } /// Save the new temporary tables in the query context for (const auto & it : query_analyzer->getExternalTables()) if (!context->tryResolveStorageID({"", it.first}, Context::ResolveExternal)) context->addExternalTable(it.first, std::move(*it.second)); } if (!options.only_analyze || options.modify_inplace) { if (syntax_analyzer_result->rewrite_subqueries) { /// remake interpreter_subquery when PredicateOptimizer rewrites subqueries and main table is subquery interpreter_subquery = joined_tables.makeLeftTableSubquery(options.subquery()); } } if (interpreter_subquery) { /// If there is an aggregation in the outer query, WITH TOTALS is ignored in the subquery. if (query_analyzer->hasAggregation()) interpreter_subquery->ignoreWithTotals(); uses_view_source |= interpreter_subquery->usesViewSource(); } required_columns = syntax_analyzer_result->requiredSourceColumns(); if (storage) { query_info.filter_asts.clear(); /// Fix source_header for filter actions. if (row_policy_filter && !row_policy_filter->empty()) { filter_info = generateFilterActions( table_id, row_policy_filter->expression, context, storage, storage_snapshot, metadata_snapshot, required_columns, prepared_sets); query_info.filter_asts.push_back(row_policy_filter->expression); } if (query_info.additional_filter_ast) { additional_filter_info = generateFilterActions( table_id, query_info.additional_filter_ast, context, storage, storage_snapshot, metadata_snapshot, required_columns, prepared_sets); additional_filter_info->do_remove_column = true; query_info.filter_asts.push_back(query_info.additional_filter_ast); } if (parallel_replicas_custom_filter_ast) { parallel_replicas_custom_filter_info = generateFilterActions( table_id, parallel_replicas_custom_filter_ast, context, storage, storage_snapshot, metadata_snapshot, required_columns, prepared_sets); parallel_replicas_custom_filter_info->do_remove_column = true; query_info.filter_asts.push_back(parallel_replicas_custom_filter_ast); } source_header = storage_snapshot->getSampleBlockForColumns(required_columns, query_info.parameterized_view_values); } /// Calculate structure of the result. result_header = getSampleBlockImpl(); }; analyze(shouldMoveToPrewhere()); bool need_analyze_again = false; bool can_analyze_again = false; if (context->hasQueryContext()) { /// Check number of calls of 'analyze' function. /// If it is too big, we will not analyze the query again not to have exponential blowup. std::atomic & current_query_analyze_count = context->getQueryContext()->kitchen_sink.analyze_counter; ++current_query_analyze_count; can_analyze_again = settings.max_analyze_depth == 0 || current_query_analyze_count < settings.max_analyze_depth; } if (can_analyze_again && (analysis_result.prewhere_constant_filter_description.always_false || analysis_result.prewhere_constant_filter_description.always_true)) { if (analysis_result.prewhere_constant_filter_description.always_true) query.setExpression(ASTSelectQuery::Expression::PREWHERE, {}); else query.setExpression(ASTSelectQuery::Expression::PREWHERE, std::make_shared(0u)); need_analyze_again = true; } if (can_analyze_again && (analysis_result.where_constant_filter_description.always_false || analysis_result.where_constant_filter_description.always_true)) { if (analysis_result.where_constant_filter_description.always_true) query.setExpression(ASTSelectQuery::Expression::WHERE, {}); else query.setExpression(ASTSelectQuery::Expression::WHERE, std::make_shared(0u)); need_analyze_again = true; } if (need_analyze_again) { size_t current_query_analyze_count = context->getQueryContext()->kitchen_sink.analyze_counter.load(); LOG_TRACE(log, "Running 'analyze' second time (current analyze depth: {})", current_query_analyze_count); /// Reuse already built sets for multiple passes of analysis prepared_sets = query_analyzer->getPreparedSets(); /// Do not try move conditions to PREWHERE for the second time. /// Otherwise, we won't be able to fallback from inefficient PREWHERE to WHERE later. analyze(/* try_move_to_prewhere = */ false); } /// If there is no WHERE, filter blocks as usual if (query.prewhere() && !query.where()) analysis_result.prewhere_info->need_filter = true; if (table_id && got_storage_from_query && !joined_tables.isLeftTableFunction()) { /// The current user should have the SELECT privilege. If this table_id is for a table /// function we don't check access rights here because in this case they have been already /// checked in ITableFunction::execute(). checkAccessRightsForSelect(context, table_id, metadata_snapshot, *syntax_analyzer_result); /// Remove limits for some tables in the `system` database. if (shouldIgnoreQuotaAndLimits(table_id) && (joined_tables.tablesCount() <= 1)) { options.ignore_quota = true; options.ignore_limits = true; } } /// Add prewhere actions with alias columns and record needed columns from storage. if (storage) { addPrewhereAliasActions(); analysis_result.required_columns = required_columns; } if (query_info.projection) storage_snapshot->addProjection(query_info.projection->desc); /// Blocks used in expression analysis contains size 1 const columns for constant folding and /// null non-const columns to avoid useless memory allocations. However, a valid block sample /// requires all columns to be of size 0, thus we need to sanitize the block here. sanitizeBlock(result_header, true); } void InterpreterSelectQuery::buildQueryPlan(QueryPlan & query_plan) { executeImpl(query_plan, std::move(input_pipe)); /// We must guarantee that result structure is the same as in getSampleBlock() /// /// But if it's a projection query, plan header does not match result_header. /// TODO: add special stage for InterpreterSelectQuery? if (!options.is_projection_query && !blocksHaveEqualStructure(query_plan.getCurrentDataStream().header, result_header)) { auto convert_actions_dag = ActionsDAG::makeConvertingActions( query_plan.getCurrentDataStream().header.getColumnsWithTypeAndName(), result_header.getColumnsWithTypeAndName(), ActionsDAG::MatchColumnsMode::Name, true); auto converting = std::make_unique(query_plan.getCurrentDataStream(), convert_actions_dag); query_plan.addStep(std::move(converting)); } /// Extend lifetime of context, table lock, storage. query_plan.addInterpreterContext(context); if (table_lock) query_plan.addTableLock(std::move(table_lock)); if (storage) query_plan.addStorageHolder(storage); } BlockIO InterpreterSelectQuery::execute() { BlockIO res; QueryPlan query_plan; buildQueryPlan(query_plan); auto builder = query_plan.buildQueryPipeline( QueryPlanOptimizationSettings::fromContext(context), BuildQueryPipelineSettings::fromContext(context)); res.pipeline = QueryPipelineBuilder::getPipeline(std::move(*builder)); setQuota(res.pipeline); return res; } Block InterpreterSelectQuery::getSampleBlockImpl() { auto & select_query = getSelectQuery(); query_info.query = query_ptr; /// NOTE: this is required for getQueryProcessingStage(), so should be initialized before ExpressionAnalysisResult. query_info.has_window = query_analyzer->hasWindow(); /// NOTE: this is required only for IStorage::read(), and to be precise MergeTreeData::read(), in case of projections. query_info.has_order_by = select_query.orderBy() != nullptr; query_info.need_aggregate = query_analyzer->hasAggregation(); if (storage && !options.only_analyze) { query_analyzer->makeSetsForIndex(select_query.where()); query_analyzer->makeSetsForIndex(select_query.prewhere()); query_info.prepared_sets = query_analyzer->getPreparedSets(); from_stage = storage->getQueryProcessingStage(context, options.to_stage, storage_snapshot, query_info); } /// Do I need to perform the first part of the pipeline? /// Running on remote servers during distributed processing or if query is not distributed. /// /// Also note that with distributed_group_by_no_merge=1 or when there is /// only one remote server, it is equal to local query in terms of query /// stages (or when due to optimize_distributed_group_by_sharding_key the query was processed up to Complete stage). bool first_stage = from_stage < QueryProcessingStage::WithMergeableState && options.to_stage >= QueryProcessingStage::WithMergeableState; /// Do I need to execute the second part of the pipeline? /// Running on the initiating server during distributed processing or if query is not distributed. /// /// Also note that with distributed_group_by_no_merge=2 (i.e. when optimize_distributed_group_by_sharding_key takes place) /// the query on the remote server will be processed up to WithMergeableStateAfterAggregationAndLimit, /// So it will do partial second stage (second_stage=true), and initiator will do the final part. bool second_stage = from_stage <= QueryProcessingStage::WithMergeableState && options.to_stage > QueryProcessingStage::WithMergeableState; analysis_result = ExpressionAnalysisResult( *query_analyzer, metadata_snapshot, first_stage, second_stage, options.only_analyze, filter_info, additional_filter_info, source_header); if (options.to_stage == QueryProcessingStage::Enum::FetchColumns) { auto header = source_header; if (analysis_result.prewhere_info) { header = analysis_result.prewhere_info->prewhere_actions->updateHeader(header); if (analysis_result.prewhere_info->remove_prewhere_column) header.erase(analysis_result.prewhere_info->prewhere_column_name); } return header; } if (options.to_stage == QueryProcessingStage::Enum::WithMergeableState) { if (!analysis_result.need_aggregate) { // What's the difference with selected_columns? // Here we calculate the header we want from remote server after it // executes query up to WithMergeableState. When there is an ORDER BY, // it is executed on remote server firstly, then we execute merge // sort on initiator. To execute ORDER BY, we need to calculate the // ORDER BY keys. These keys might be not present among the final // SELECT columns given by the `selected_column`. This is why we have // to use proper keys given by the result columns of the // `before_order_by` expression actions. // Another complication is window functions -- if we have them, they // are calculated on initiator, before ORDER BY columns. In this case, // the shard has to return columns required for window function // calculation and further steps, given by the `before_window` // expression actions. // As of 21.6 this is broken: the actions in `before_window` might // not contain everything required for the ORDER BY step, but this // is a responsibility of ExpressionAnalyzer and is not a problem // with this code. See // https://github.com/ClickHouse/ClickHouse/issues/19857 for details. if (analysis_result.before_window) return analysis_result.before_window->getResultColumns(); return analysis_result.before_order_by->getResultColumns(); } Block header = analysis_result.before_aggregation->getResultColumns(); Block res; if (analysis_result.use_grouping_set_key) res.insert({ nullptr, std::make_shared(), "__grouping_set" }); if (context->getSettingsRef().group_by_use_nulls && analysis_result.use_grouping_set_key) { for (const auto & key : query_analyzer->aggregationKeys()) res.insert({nullptr, makeNullableSafe(header.getByName(key.name).type), key.name}); } else { for (const auto & key : query_analyzer->aggregationKeys()) res.insert({nullptr, header.getByName(key.name).type, key.name}); } for (const auto & aggregate : query_analyzer->aggregates()) { size_t arguments_size = aggregate.argument_names.size(); DataTypes argument_types(arguments_size); for (size_t j = 0; j < arguments_size; ++j) argument_types[j] = header.getByName(aggregate.argument_names[j]).type; DataTypePtr type = std::make_shared(aggregate.function, argument_types, aggregate.parameters); res.insert({nullptr, type, aggregate.column_name}); } return res; } if (options.to_stage >= QueryProcessingStage::Enum::WithMergeableStateAfterAggregation) { // It's different from selected_columns, see the comment above for // WithMergeableState stage. if (analysis_result.before_window) return analysis_result.before_window->getResultColumns(); return analysis_result.before_order_by->getResultColumns(); } return analysis_result.final_projection->getResultColumns(); } static std::pair getWithFillFieldValue(const ASTPtr & node, ContextPtr context) { auto field_type = evaluateConstantExpression(node, context); if (!isColumnedAsNumber(field_type.second)) throw Exception(ErrorCodes::INVALID_WITH_FILL_EXPRESSION, "Illegal type {} of WITH FILL expression, must be numeric type", field_type.second->getName()); return field_type; } static std::pair> getWithFillStep(const ASTPtr & node, const ContextPtr & context) { auto [field, type] = evaluateConstantExpression(node, context); if (const auto * type_interval = typeid_cast(type.get())) return std::make_pair(std::move(field), type_interval->getKind()); if (isColumnedAsNumber(type)) return std::make_pair(std::move(field), std::nullopt); throw Exception(ErrorCodes::INVALID_WITH_FILL_EXPRESSION, "Illegal type {} of WITH FILL expression, must be numeric type", type->getName()); } static FillColumnDescription getWithFillDescription(const ASTOrderByElement & order_by_elem, const ContextPtr & context) { FillColumnDescription descr; if (order_by_elem.fill_from) std::tie(descr.fill_from, descr.fill_from_type) = getWithFillFieldValue(order_by_elem.fill_from, context); if (order_by_elem.fill_to) std::tie(descr.fill_to, descr.fill_to_type) = getWithFillFieldValue(order_by_elem.fill_to, context); if (order_by_elem.fill_step) std::tie(descr.fill_step, descr.step_kind) = getWithFillStep(order_by_elem.fill_step, context); else descr.fill_step = order_by_elem.direction; if (applyVisitor(FieldVisitorAccurateEquals(), descr.fill_step, Field{0})) throw Exception(ErrorCodes::INVALID_WITH_FILL_EXPRESSION, "WITH FILL STEP value cannot be zero"); if (order_by_elem.direction == 1) { if (applyVisitor(FieldVisitorAccurateLess(), descr.fill_step, Field{0})) throw Exception(ErrorCodes::INVALID_WITH_FILL_EXPRESSION, "WITH FILL STEP value cannot be negative for sorting in ascending direction"); if (!descr.fill_from.isNull() && !descr.fill_to.isNull() && applyVisitor(FieldVisitorAccurateLess(), descr.fill_to, descr.fill_from)) { throw Exception(ErrorCodes::INVALID_WITH_FILL_EXPRESSION, "WITH FILL TO value cannot be less than FROM value for sorting in ascending direction"); } } else { if (applyVisitor(FieldVisitorAccurateLess(), Field{0}, descr.fill_step)) throw Exception(ErrorCodes::INVALID_WITH_FILL_EXPRESSION, "WITH FILL STEP value cannot be positive for sorting in descending direction"); if (!descr.fill_from.isNull() && !descr.fill_to.isNull() && applyVisitor(FieldVisitorAccurateLess(), descr.fill_from, descr.fill_to)) { throw Exception(ErrorCodes::INVALID_WITH_FILL_EXPRESSION, "WITH FILL FROM value cannot be less than TO value for sorting in descending direction"); } } return descr; } SortDescription InterpreterSelectQuery::getSortDescription(const ASTSelectQuery & query, const ContextPtr & context_) { SortDescription order_descr; order_descr.reserve(query.orderBy()->children.size()); for (const auto & elem : query.orderBy()->children) { const String & column_name = elem->children.front()->getColumnName(); const auto & order_by_elem = elem->as(); std::shared_ptr collator; if (order_by_elem.collation) collator = std::make_shared(order_by_elem.collation->as().value.get()); if (order_by_elem.with_fill) { FillColumnDescription fill_desc = getWithFillDescription(order_by_elem, context_); order_descr.emplace_back(column_name, order_by_elem.direction, order_by_elem.nulls_direction, collator, true, fill_desc); } else order_descr.emplace_back(column_name, order_by_elem.direction, order_by_elem.nulls_direction, collator); } order_descr.compile_sort_description = context_->getSettingsRef().compile_sort_description; order_descr.min_count_to_compile_sort_description = context_->getSettingsRef().min_count_to_compile_sort_description; return order_descr; } static InterpolateDescriptionPtr getInterpolateDescription( const ASTSelectQuery & query, const Block & source_block, const Block & result_block, const Aliases & aliases, ContextPtr context) { InterpolateDescriptionPtr interpolate_descr; if (query.interpolate()) { NamesAndTypesList source_columns; ColumnsWithTypeAndName result_columns; ASTPtr exprs = std::make_shared(); if (query.interpolate()->children.empty()) { std::unordered_map column_names; for (const auto & column : result_block.getColumnsWithTypeAndName()) column_names[column.name] = column.type; for (const auto & elem : query.orderBy()->children) if (elem->as()->with_fill) column_names.erase(elem->as()->children.front()->getColumnName()); for (const auto & [name, type] : column_names) { source_columns.emplace_back(name, type); result_columns.emplace_back(type, name); exprs->children.emplace_back(std::make_shared(name)); } } else { NameSet col_set; for (const auto & elem : query.interpolate()->children) { const auto & interpolate = elem->as(); if (const ColumnWithTypeAndName *result_block_column = result_block.findByName(interpolate.column)) { if (!col_set.insert(result_block_column->name).second) throw Exception(ErrorCodes::INVALID_WITH_FILL_EXPRESSION, "Duplicate INTERPOLATE column '{}'", interpolate.column); result_columns.emplace_back(result_block_column->type, result_block_column->name); } else throw Exception(ErrorCodes::UNKNOWN_IDENTIFIER, "Missing column '{}' as an INTERPOLATE expression target", interpolate.column); exprs->children.emplace_back(interpolate.expr->clone()); } col_set.clear(); for (const auto & column : source_block) { source_columns.emplace_back(column.name, column.type); col_set.insert(column.name); } for (const auto & column : result_block) if (!col_set.contains(column.name)) source_columns.emplace_back(column.name, column.type); } auto syntax_result = TreeRewriter(context).analyze(exprs, source_columns); ExpressionAnalyzer analyzer(exprs, syntax_result, context); ActionsDAGPtr actions = analyzer.getActionsDAG(true); ActionsDAGPtr conv_dag = ActionsDAG::makeConvertingActions(actions->getResultColumns(), result_columns, ActionsDAG::MatchColumnsMode::Position, true); ActionsDAGPtr merge_dag = ActionsDAG::merge(std::move(*actions->clone()), std::move(*conv_dag)); interpolate_descr = std::make_shared(merge_dag, aliases); } return interpolate_descr; } static SortDescription getSortDescriptionFromGroupBy(const ASTSelectQuery & query) { if (!query.groupBy()) return {}; SortDescription order_descr; order_descr.reserve(query.groupBy()->children.size()); for (const auto & elem : query.groupBy()->children) { String name = elem->getColumnName(); order_descr.emplace_back(name, 1, 1); } return order_descr; } static UInt64 getLimitUIntValue(const ASTPtr & node, const ContextPtr & context, const std::string & expr) { const auto & [field, type] = evaluateConstantExpression(node, context); if (!isNativeNumber(type)) throw Exception(ErrorCodes::INVALID_LIMIT_EXPRESSION, "Illegal type {} of {} expression, must be numeric type", type->getName(), expr); Field converted = convertFieldToType(field, DataTypeUInt64()); if (converted.isNull()) throw Exception(ErrorCodes::INVALID_LIMIT_EXPRESSION, "The value {} of {} expression is not representable as UInt64", applyVisitor(FieldVisitorToString(), field), expr); return converted.safeGet(); } static std::pair getLimitLengthAndOffset(const ASTSelectQuery & query, const ContextPtr & context) { UInt64 length = 0; UInt64 offset = 0; if (query.limitLength()) { length = getLimitUIntValue(query.limitLength(), context, "LIMIT"); if (query.limitOffset() && length) offset = getLimitUIntValue(query.limitOffset(), context, "OFFSET"); } else if (query.limitOffset()) offset = getLimitUIntValue(query.limitOffset(), context, "OFFSET"); return {length, offset}; } UInt64 InterpreterSelectQuery::getLimitForSorting(const ASTSelectQuery & query, const ContextPtr & context_) { /// Partial sort can be done if there is LIMIT but no DISTINCT or LIMIT BY, neither ARRAY JOIN. if (!query.distinct && !query.limitBy() && !query.limit_with_ties && !query.arrayJoinExpressionList().first && query.limitLength()) { auto [limit_length, limit_offset] = getLimitLengthAndOffset(query, context_); if (limit_length > std::numeric_limits::max() - limit_offset) return 0; return limit_length + limit_offset; } return 0; } static bool hasWithTotalsInAnySubqueryInFromClause(const ASTSelectQuery & query) { if (query.group_by_with_totals) return true; /** NOTE You can also check that the table in the subquery is distributed, and that it only looks at one shard. * In other cases, totals will be computed on the initiating server of the query, and it is not necessary to read the data to the end. */ if (auto query_table = extractTableExpression(query, 0)) { if (const auto * ast_union = query_table->as()) { /** NOTE * 1. For ASTSelectWithUnionQuery after normalization for union child node the height of the AST tree is at most 2. * 2. For ASTSelectIntersectExceptQuery after normalization in case there are intersect or except nodes, * the height of the AST tree can have any depth (each intersect/except adds a level), but the * number of children in those nodes is always 2. */ std::function traverse_recursively = [&](ASTPtr child_ast) -> bool { if (const auto * select_child = child_ast->as ()) { if (hasWithTotalsInAnySubqueryInFromClause(select_child->as())) return true; } else if (const auto * union_child = child_ast->as()) { for (const auto & subchild : union_child->list_of_selects->children) if (traverse_recursively(subchild)) return true; } else if (const auto * intersect_child = child_ast->as()) { auto selects = intersect_child->getListOfSelects(); for (const auto & subchild : selects) if (traverse_recursively(subchild)) return true; } return false; }; for (const auto & elem : ast_union->list_of_selects->children) if (traverse_recursively(elem)) return true; } } return false; } void InterpreterSelectQuery::executeImpl(QueryPlan & query_plan, std::optional prepared_pipe) { /** Streams of data. When the query is executed in parallel, we have several data streams. * If there is no GROUP BY, then perform all operations before ORDER BY and LIMIT in parallel, then * if there is an ORDER BY, then glue the streams using ResizeProcessor, and then MergeSorting transforms, * if not, then glue it using ResizeProcessor, * then apply LIMIT. * If there is GROUP BY, then we will perform all operations up to GROUP BY, inclusive, in parallel; * a parallel GROUP BY will glue streams into one, * then perform the remaining operations with one resulting stream. */ /// Now we will compose block streams that perform the necessary actions. auto & query = getSelectQuery(); const Settings & settings = context->getSettingsRef(); auto & expressions = analysis_result; bool intermediate_stage = false; bool to_aggregation_stage = false; bool from_aggregation_stage = false; /// Do I need to aggregate in a separate row that has not passed max_rows_to_group_by? bool aggregate_overflow_row = expressions.need_aggregate && query.group_by_with_totals && settings.max_rows_to_group_by && settings.group_by_overflow_mode == OverflowMode::ANY && settings.totals_mode != TotalsMode::AFTER_HAVING_EXCLUSIVE; /// Do I need to immediately finalize the aggregate functions after the aggregation? bool aggregate_final = expressions.need_aggregate && options.to_stage > QueryProcessingStage::WithMergeableState && !query.group_by_with_totals && !query.group_by_with_rollup && !query.group_by_with_cube; bool use_grouping_set_key = expressions.use_grouping_set_key; if (query.group_by_with_grouping_sets && query.group_by_with_totals) throw Exception(ErrorCodes::NOT_IMPLEMENTED, "WITH TOTALS and GROUPING SETS are not supported together"); if (query.group_by_with_grouping_sets && (query.group_by_with_rollup || query.group_by_with_cube)) throw Exception(ErrorCodes::NOT_IMPLEMENTED, "GROUPING SETS are not supported together with ROLLUP and CUBE"); if (expressions.hasHaving() && query.group_by_with_totals && (query.group_by_with_rollup || query.group_by_with_cube)) throw Exception(ErrorCodes::NOT_IMPLEMENTED, "WITH TOTALS and WITH ROLLUP or CUBE are not supported together in presence of HAVING"); if (query_info.projection && query_info.projection->desc->type == ProjectionDescription::Type::Aggregate) { query_info.projection->aggregate_overflow_row = aggregate_overflow_row; query_info.projection->aggregate_final = aggregate_final; } if (options.only_analyze) { auto read_nothing = std::make_unique(source_header); query_plan.addStep(std::move(read_nothing)); if (expressions.filter_info) { auto row_level_security_step = std::make_unique( query_plan.getCurrentDataStream(), expressions.filter_info->actions, expressions.filter_info->column_name, expressions.filter_info->do_remove_column); row_level_security_step->setStepDescription("Row-level security filter"); query_plan.addStep(std::move(row_level_security_step)); } if (expressions.prewhere_info) { if (expressions.prewhere_info->row_level_filter) { auto row_level_filter_step = std::make_unique( query_plan.getCurrentDataStream(), expressions.prewhere_info->row_level_filter, expressions.prewhere_info->row_level_column_name, true); row_level_filter_step->setStepDescription("Row-level security filter (PREWHERE)"); query_plan.addStep(std::move(row_level_filter_step)); } auto prewhere_step = std::make_unique( query_plan.getCurrentDataStream(), expressions.prewhere_info->prewhere_actions, expressions.prewhere_info->prewhere_column_name, expressions.prewhere_info->remove_prewhere_column); prewhere_step->setStepDescription("PREWHERE"); query_plan.addStep(std::move(prewhere_step)); } } else { if (prepared_pipe) { auto prepared_source_step = std::make_unique(std::move(*prepared_pipe)); query_plan.addStep(std::move(prepared_source_step)); query_plan.addInterpreterContext(context); } if (from_stage == QueryProcessingStage::WithMergeableState && options.to_stage == QueryProcessingStage::WithMergeableState) intermediate_stage = true; /// Support optimize_distributed_group_by_sharding_key /// Is running on the initiating server during distributed processing? if (from_stage >= QueryProcessingStage::WithMergeableStateAfterAggregation) from_aggregation_stage = true; /// Is running on remote servers during distributed processing? if (options.to_stage >= QueryProcessingStage::WithMergeableStateAfterAggregation) to_aggregation_stage = true; /// Read the data from Storage. from_stage - to what stage the request was completed in Storage. executeFetchColumns(from_stage, query_plan); LOG_TRACE(log, "{} -> {}", QueryProcessingStage::toString(from_stage), QueryProcessingStage::toString(options.to_stage)); } if (query_info.projection && query_info.projection->input_order_info && query_info.input_order_info) throw Exception(ErrorCodes::LOGICAL_ERROR, "InputOrderInfo is set for projection and for query"); InputOrderInfoPtr input_order_info_for_order; if (!expressions.need_aggregate) input_order_info_for_order = query_info.projection ? query_info.projection->input_order_info : query_info.input_order_info; if (options.to_stage > QueryProcessingStage::FetchColumns) { auto preliminary_sort = [&]() { /** For distributed query processing, * if no GROUP, HAVING set, * but there is an ORDER or LIMIT, * then we will perform the preliminary sorting and LIMIT on the remote server. */ if (!expressions.second_stage && !expressions.need_aggregate && !expressions.hasHaving() && !expressions.has_window) { if (expressions.has_order_by) executeOrder(query_plan, input_order_info_for_order); /// pre_distinct = false, because if we have limit and distinct, /// we need to merge streams to one and calculate overall distinct. /// Otherwise we can take several equal values from different streams /// according to limit and skip some distinct values. if (query.limitLength()) executeDistinct(query_plan, false, expressions.selected_columns, false); if (expressions.hasLimitBy()) { executeExpression(query_plan, expressions.before_limit_by, "Before LIMIT BY"); executeLimitBy(query_plan); } if (query.limitLength()) executePreLimit(query_plan, true); } }; if (intermediate_stage) { if (expressions.first_stage || expressions.second_stage) throw Exception(ErrorCodes::LOGICAL_ERROR, "Query with intermediate stage cannot have any other stages"); preliminary_sort(); if (expressions.need_aggregate) executeMergeAggregated(query_plan, aggregate_overflow_row, aggregate_final, use_grouping_set_key); } if (from_aggregation_stage) { if (intermediate_stage || expressions.first_stage || expressions.second_stage) throw Exception(ErrorCodes::LOGICAL_ERROR, "Query with after aggregation stage cannot have any other stages"); } if (expressions.first_stage) { // If there is a storage that supports prewhere, this will always be nullptr // Thus, we don't actually need to check if projection is active. if (!query_info.projection && expressions.filter_info) { auto row_level_security_step = std::make_unique( query_plan.getCurrentDataStream(), expressions.filter_info->actions, expressions.filter_info->column_name, expressions.filter_info->do_remove_column); row_level_security_step->setStepDescription("Row-level security filter"); query_plan.addStep(std::move(row_level_security_step)); } const auto add_filter_step = [&](const auto & new_filter_info, const std::string & description) { auto filter_step = std::make_unique( query_plan.getCurrentDataStream(), new_filter_info->actions, new_filter_info->column_name, new_filter_info->do_remove_column); filter_step->setStepDescription(description); query_plan.addStep(std::move(filter_step)); }; if (additional_filter_info) add_filter_step(additional_filter_info, "Additional filter"); if (parallel_replicas_custom_filter_info) add_filter_step(parallel_replicas_custom_filter_info, "Parallel replica custom key filter"); if (expressions.before_array_join) { QueryPlanStepPtr before_array_join_step = std::make_unique(query_plan.getCurrentDataStream(), expressions.before_array_join); before_array_join_step->setStepDescription("Before ARRAY JOIN"); query_plan.addStep(std::move(before_array_join_step)); } if (expressions.array_join) { QueryPlanStepPtr array_join_step = std::make_unique(query_plan.getCurrentDataStream(), expressions.array_join); array_join_step->setStepDescription("ARRAY JOIN"); query_plan.addStep(std::move(array_join_step)); } if (expressions.before_join) { QueryPlanStepPtr before_join_step = std::make_unique( query_plan.getCurrentDataStream(), expressions.before_join); before_join_step->setStepDescription("Before JOIN"); query_plan.addStep(std::move(before_join_step)); } /// Optional step to convert key columns to common supertype. if (expressions.converting_join_columns) { QueryPlanStepPtr convert_join_step = std::make_unique( query_plan.getCurrentDataStream(), expressions.converting_join_columns); convert_join_step->setStepDescription("Convert JOIN columns"); query_plan.addStep(std::move(convert_join_step)); } if (expressions.hasJoin()) { if (expressions.join->isFilled()) { QueryPlanStepPtr filled_join_step = std::make_unique( query_plan.getCurrentDataStream(), expressions.join, settings.max_block_size); filled_join_step->setStepDescription("JOIN"); query_plan.addStep(std::move(filled_join_step)); } else { auto joined_plan = query_analyzer->getJoinedPlan(); if (!joined_plan) throw Exception(ErrorCodes::LOGICAL_ERROR, "There is no joined plan for query"); auto add_sorting = [&settings, this] (QueryPlan & plan, const Names & key_names, JoinTableSide join_pos) { SortDescription order_descr; order_descr.reserve(key_names.size()); for (const auto & key_name : key_names) order_descr.emplace_back(key_name); SortingStep::Settings sort_settings(*context); auto sorting_step = std::make_unique( plan.getCurrentDataStream(), std::move(order_descr), 0 /* LIMIT */, sort_settings, settings.optimize_sorting_by_input_stream_properties); sorting_step->setStepDescription(fmt::format("Sort {} before JOIN", join_pos)); plan.addStep(std::move(sorting_step)); }; auto crosswise_connection = CreateSetAndFilterOnTheFlyStep::createCrossConnection(); auto add_create_set = [&settings, crosswise_connection](QueryPlan & plan, const Names & key_names, JoinTableSide join_pos) { auto creating_set_step = std::make_unique( plan.getCurrentDataStream(), key_names, settings.max_rows_in_set_to_optimize_join, crosswise_connection, join_pos); creating_set_step->setStepDescription(fmt::format("Create set and filter {} joined stream", join_pos)); auto * step_raw_ptr = creating_set_step.get(); plan.addStep(std::move(creating_set_step)); return step_raw_ptr; }; if (expressions.join->pipelineType() == JoinPipelineType::YShaped) { const auto & table_join = expressions.join->getTableJoin(); const auto & join_clause = table_join.getOnlyClause(); auto join_kind = table_join.kind(); bool kind_allows_filtering = isInner(join_kind) || isLeft(join_kind) || isRight(join_kind); auto has_non_const = [](const Block & block, const auto & keys) { for (const auto & key : keys) { const auto & column = block.getByName(key).column; if (column && !isColumnConst(*column)) return true; } return false; }; /// This optimization relies on the sorting that should buffer the whole stream before emitting any rows. /// It doesn't hold such a guarantee for streams with const keys. /// Note: it's also doesn't work with the read-in-order optimization. /// No checks here because read in order is not applied if we have `CreateSetAndFilterOnTheFlyStep` in the pipeline between the reading and sorting steps. bool has_non_const_keys = has_non_const(query_plan.getCurrentDataStream().header, join_clause.key_names_left) && has_non_const(joined_plan->getCurrentDataStream().header, join_clause.key_names_right); if (settings.max_rows_in_set_to_optimize_join > 0 && kind_allows_filtering && has_non_const_keys) { auto * left_set = add_create_set(query_plan, join_clause.key_names_left, JoinTableSide::Left); auto * right_set = add_create_set(*joined_plan, join_clause.key_names_right, JoinTableSide::Right); if (isInnerOrLeft(join_kind)) right_set->setFiltering(left_set->getSet()); if (isInnerOrRight(join_kind)) left_set->setFiltering(right_set->getSet()); } add_sorting(query_plan, join_clause.key_names_left, JoinTableSide::Left); add_sorting(*joined_plan, join_clause.key_names_right, JoinTableSide::Right); } QueryPlanStepPtr join_step = std::make_unique( query_plan.getCurrentDataStream(), joined_plan->getCurrentDataStream(), expressions.join, settings.max_block_size, max_streams, analysis_result.optimize_read_in_order); join_step->setStepDescription(fmt::format("JOIN {}", expressions.join->pipelineType())); std::vector plans; plans.emplace_back(std::make_unique(std::move(query_plan))); plans.emplace_back(std::move(joined_plan)); query_plan = QueryPlan(); query_plan.unitePlans(std::move(join_step), {std::move(plans)}); } } if (!query_info.projection && expressions.hasWhere()) executeWhere(query_plan, expressions.before_where, expressions.remove_where_filter); if (expressions.need_aggregate) executeAggregation( query_plan, expressions.before_aggregation, aggregate_overflow_row, aggregate_final, query_info.input_order_info); // Now we must execute: // 1) expressions before window functions, // 2) window functions, // 3) expressions after window functions, // 4) preliminary distinct. // This code decides which part we execute on shard (first_stage) // and which part on initiator (second_stage). See also the counterpart // code for "second_stage" that has to execute the rest. if (expressions.need_aggregate) { // We have aggregation, so we can't execute any later-stage // expressions on shards, neither "before window functions" nor // "before ORDER BY". } else { // We don't have aggregation. // Window functions must be executed on initiator (second_stage). // ORDER BY and DISTINCT might depend on them, so if we have // window functions, we can't execute ORDER BY and DISTINCT // now, on shard (first_stage). if (query_analyzer->hasWindow()) { executeExpression(query_plan, expressions.before_window, "Before window functions"); } else { // We don't have window functions, so we can execute the // expressions before ORDER BY and the preliminary DISTINCT // now, on shards (first_stage). assert(!expressions.before_window); executeExpression(query_plan, expressions.before_order_by, "Before ORDER BY"); executeDistinct(query_plan, true, expressions.selected_columns, true); } } preliminary_sort(); } if (expressions.second_stage || from_aggregation_stage) { if (from_aggregation_stage) { /// No need to aggregate anything, since this was done on remote shards. } else if (expressions.need_aggregate) { /// If you need to combine aggregated results from multiple servers if (!expressions.first_stage) executeMergeAggregated(query_plan, aggregate_overflow_row, aggregate_final, use_grouping_set_key); if (!aggregate_final) { if (query.group_by_with_totals) { bool final = !query.group_by_with_rollup && !query.group_by_with_cube; executeTotalsAndHaving( query_plan, expressions.hasHaving(), expressions.before_having, expressions.remove_having_filter, aggregate_overflow_row, final); } if (query.group_by_with_rollup) executeRollupOrCube(query_plan, Modificator::ROLLUP); else if (query.group_by_with_cube) executeRollupOrCube(query_plan, Modificator::CUBE); if ((query.group_by_with_rollup || query.group_by_with_cube || query.group_by_with_grouping_sets) && expressions.hasHaving()) executeHaving(query_plan, expressions.before_having, expressions.remove_having_filter); } else if (expressions.hasHaving()) executeHaving(query_plan, expressions.before_having, expressions.remove_having_filter); } else if (query.group_by_with_totals || query.group_by_with_rollup || query.group_by_with_cube || query.group_by_with_grouping_sets) throw Exception(ErrorCodes::NOT_IMPLEMENTED, "WITH TOTALS, ROLLUP, CUBE or GROUPING SETS are not supported without aggregation"); // Now we must execute: // 1) expressions before window functions, // 2) window functions, // 3) expressions after window functions, // 4) preliminary distinct. // Some of these were already executed at the shards (first_stage), // see the counterpart code and comments there. if (from_aggregation_stage) { if (query_analyzer->hasWindow()) throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Window functions does not support processing from WithMergeableStateAfterAggregation"); } else if (expressions.need_aggregate) { executeExpression(query_plan, expressions.before_window, "Before window functions"); executeWindow(query_plan); executeExpression(query_plan, expressions.before_order_by, "Before ORDER BY"); executeDistinct(query_plan, true, expressions.selected_columns, true); } else { if (query_analyzer->hasWindow()) { executeWindow(query_plan); executeExpression(query_plan, expressions.before_order_by, "Before ORDER BY"); executeDistinct(query_plan, true, expressions.selected_columns, true); } else { // Neither aggregation nor windows, all expressions before // ORDER BY executed on shards. } } if (expressions.has_order_by) { /** If there is an ORDER BY for distributed query processing, * but there is no aggregation, then on the remote servers ORDER BY was made * - therefore, we merge the sorted streams from remote servers. * * Also in case of remote servers was process the query up to WithMergeableStateAfterAggregationAndLimit * (distributed_group_by_no_merge=2 or optimize_distributed_group_by_sharding_key=1 takes place), * then merge the sorted streams is enough, since remote servers already did full ORDER BY. */ if (from_aggregation_stage) executeMergeSorted(query_plan, "after aggregation stage for ORDER BY"); else if (!expressions.first_stage && !expressions.need_aggregate && !expressions.has_window && !(query.group_by_with_totals && !aggregate_final)) executeMergeSorted(query_plan, "for ORDER BY, without aggregation"); else /// Otherwise, just sort. executeOrder(query_plan, input_order_info_for_order); } /** Optimization - if there are several sources and there is LIMIT, then first apply the preliminary LIMIT, * limiting the number of rows in each up to `offset + limit`. */ bool has_withfill = false; if (query.orderBy()) { SortDescription order_descr = getSortDescription(query, context); for (auto & desc : order_descr) if (desc.with_fill) { has_withfill = true; break; } } bool apply_limit = options.to_stage != QueryProcessingStage::WithMergeableStateAfterAggregation; bool apply_prelimit = apply_limit && query.limitLength() && !query.limit_with_ties && !hasWithTotalsInAnySubqueryInFromClause(query) && !query.arrayJoinExpressionList().first && !query.distinct && !expressions.hasLimitBy() && !settings.extremes && !has_withfill; bool apply_offset = options.to_stage != QueryProcessingStage::WithMergeableStateAfterAggregationAndLimit; if (apply_prelimit) { executePreLimit(query_plan, /* do_not_skip_offset= */!apply_offset); } /** If there was more than one stream, * then DISTINCT needs to be performed once again after merging all streams. */ if (!from_aggregation_stage && query.distinct) executeDistinct(query_plan, false, expressions.selected_columns, false); if (!from_aggregation_stage && expressions.hasLimitBy()) { executeExpression(query_plan, expressions.before_limit_by, "Before LIMIT BY"); executeLimitBy(query_plan); } executeWithFill(query_plan); /// If we have 'WITH TIES', we need execute limit before projection, /// because in that case columns from 'ORDER BY' are used. if (query.limit_with_ties && apply_offset) { executeLimit(query_plan); } /// Projection not be done on the shards, since then initiator will not find column in blocks. /// (significant only for WithMergeableStateAfterAggregation/WithMergeableStateAfterAggregationAndLimit). if (!to_aggregation_stage) { /// We must do projection after DISTINCT because projection may remove some columns. executeProjection(query_plan, expressions.final_projection); } /// Extremes are calculated before LIMIT, but after LIMIT BY. This is Ok. executeExtremes(query_plan); bool limit_applied = apply_prelimit || (query.limit_with_ties && apply_offset); /// Limit is no longer needed if there is prelimit. /// /// NOTE: that LIMIT cannot be applied if OFFSET should not be applied, /// since LIMIT will apply OFFSET too. /// This is the case for various optimizations for distributed queries, /// and when LIMIT cannot be applied it will be applied on the initiator anyway. if (apply_limit && !limit_applied && apply_offset) executeLimit(query_plan); if (apply_offset) executeOffset(query_plan); } } executeSubqueriesInSetsAndJoins(query_plan); } static void executeMergeAggregatedImpl( QueryPlan & query_plan, bool overflow_row, bool final, bool is_remote_storage, bool has_grouping_sets, const Settings & settings, const NamesAndTypesList & aggregation_keys, const AggregateDescriptions & aggregates, bool should_produce_results_in_order_of_bucket_number, SortDescription group_by_sort_description) { auto keys = aggregation_keys.getNames(); if (has_grouping_sets) keys.insert(keys.begin(), "__grouping_set"); /** There are two modes of distributed aggregation. * * 1. In different threads read from the remote servers blocks. * Save all the blocks in the RAM. Merge blocks. * If the aggregation is two-level - parallelize to the number of buckets. * * 2. In one thread, read blocks from different servers in order. * RAM stores only one block from each server. * If the aggregation is a two-level aggregation, we consistently merge the blocks of each next level. * * The second option consumes less memory (up to 256 times less) * in the case of two-level aggregation, which is used for large results after GROUP BY, * but it can work more slowly. */ Aggregator::Params params(keys, aggregates, overflow_row, settings.max_threads, settings.max_block_size); auto merging_aggregated = std::make_unique( query_plan.getCurrentDataStream(), params, final, /// Grouping sets don't work with distributed_aggregation_memory_efficient enabled (#43989) settings.distributed_aggregation_memory_efficient && is_remote_storage && !has_grouping_sets, settings.max_threads, settings.aggregation_memory_efficient_merge_threads, should_produce_results_in_order_of_bucket_number, settings.max_block_size, settings.aggregation_in_order_max_block_bytes, std::move(group_by_sort_description), settings.enable_memory_bound_merging_of_aggregation_results); query_plan.addStep(std::move(merging_aggregated)); } void InterpreterSelectQuery::addEmptySourceToQueryPlan( QueryPlan & query_plan, const Block & source_header, const SelectQueryInfo & query_info, const ContextPtr & context_) { Pipe pipe(std::make_shared(source_header)); PrewhereInfoPtr prewhere_info_ptr = query_info.projection ? query_info.projection->prewhere_info : query_info.prewhere_info; if (prewhere_info_ptr) { auto & prewhere_info = *prewhere_info_ptr; if (prewhere_info.row_level_filter) { pipe.addSimpleTransform([&](const Block & header) { return std::make_shared(header, std::make_shared(prewhere_info.row_level_filter), prewhere_info.row_level_column_name, true); }); } pipe.addSimpleTransform([&](const Block & header) { return std::make_shared( header, std::make_shared(prewhere_info.prewhere_actions), prewhere_info.prewhere_column_name, prewhere_info.remove_prewhere_column); }); } auto read_from_pipe = std::make_unique(std::move(pipe)); read_from_pipe->setStepDescription("Read from NullSource"); query_plan.addStep(std::move(read_from_pipe)); if (query_info.projection) { if (query_info.projection->before_where) { auto where_step = std::make_unique( query_plan.getCurrentDataStream(), query_info.projection->before_where, query_info.projection->where_column_name, query_info.projection->remove_where_filter); where_step->setStepDescription("WHERE"); query_plan.addStep(std::move(where_step)); } if (query_info.projection->desc->type == ProjectionDescription::Type::Aggregate) { if (query_info.projection->before_aggregation) { auto expression_before_aggregation = std::make_unique(query_plan.getCurrentDataStream(), query_info.projection->before_aggregation); expression_before_aggregation->setStepDescription("Before GROUP BY"); query_plan.addStep(std::move(expression_before_aggregation)); } // Let's just choose the safe option since we don't know the value of `to_stage` here. const bool should_produce_results_in_order_of_bucket_number = true; // It is used to determine if we should use memory bound merging strategy. Maybe it makes sense for projections, but so far this case is just left untouched. SortDescription group_by_sort_description; executeMergeAggregatedImpl( query_plan, query_info.projection->aggregate_overflow_row, query_info.projection->aggregate_final, false, false, context_->getSettingsRef(), query_info.projection->aggregation_keys, query_info.projection->aggregate_descriptions, should_produce_results_in_order_of_bucket_number, std::move(group_by_sort_description)); } } } RowPolicyFilterPtr InterpreterSelectQuery::getRowPolicyFilter() const { return row_policy_filter; } void InterpreterSelectQuery::extendQueryLogElemImpl(QueryLogElement & elem, const ASTPtr & /*ast*/, ContextPtr /*context_*/) const { for (const auto & row_policy : row_policy_filter->policies) { auto name = row_policy->getFullName().toString(); elem.used_row_policies.emplace(std::move(name)); } } bool InterpreterSelectQuery::shouldMoveToPrewhere() { const Settings & settings = context->getSettingsRef(); const ASTSelectQuery & query = getSelectQuery(); return settings.optimize_move_to_prewhere && (!query.final() || settings.optimize_move_to_prewhere_if_final); } void InterpreterSelectQuery::addPrewhereAliasActions() { auto & expressions = analysis_result; if (expressions.filter_info) { if (!expressions.prewhere_info) { const bool does_storage_support_prewhere = !input_pipe && storage && storage->supportsPrewhere(); if (does_storage_support_prewhere && shouldMoveToPrewhere()) { /// Execute row level filter in prewhere as a part of "move to prewhere" optimization. expressions.prewhere_info = std::make_shared( std::move(expressions.filter_info->actions), std::move(expressions.filter_info->column_name)); expressions.prewhere_info->prewhere_actions->projectInput(false); expressions.prewhere_info->remove_prewhere_column = expressions.filter_info->do_remove_column; expressions.prewhere_info->need_filter = true; expressions.filter_info = nullptr; } } else { /// Add row level security actions to prewhere. expressions.prewhere_info->row_level_filter = std::move(expressions.filter_info->actions); expressions.prewhere_info->row_level_column_name = std::move(expressions.filter_info->column_name); expressions.prewhere_info->row_level_filter->projectInput(false); expressions.filter_info = nullptr; } } auto & prewhere_info = analysis_result.prewhere_info; auto & columns_to_remove_after_prewhere = analysis_result.columns_to_remove_after_prewhere; /// Detect, if ALIAS columns are required for query execution auto alias_columns_required = false; const ColumnsDescription & storage_columns = metadata_snapshot->getColumns(); for (const auto & column_name : required_columns) { auto column_default = storage_columns.getDefault(column_name); if (column_default && column_default->kind == ColumnDefaultKind::Alias) { alias_columns_required = true; break; } } /// Set of all (including ALIAS) required columns for PREWHERE auto get_prewhere_columns = [&]() { NameSet columns; if (prewhere_info) { /// Get some columns directly from PREWHERE expression actions auto prewhere_required_columns = prewhere_info->prewhere_actions->getRequiredColumns().getNames(); columns.insert(prewhere_required_columns.begin(), prewhere_required_columns.end()); if (prewhere_info->row_level_filter) { auto row_level_required_columns = prewhere_info->row_level_filter->getRequiredColumns().getNames(); columns.insert(row_level_required_columns.begin(), row_level_required_columns.end()); } } return columns; }; /// There are multiple sources of required columns: /// - raw required columns, /// - columns deduced from ALIAS columns, /// - raw required columns from PREWHERE, /// - columns deduced from ALIAS columns from PREWHERE. /// PREWHERE is a special case, since we need to resolve it and pass directly to `IStorage::read()` /// before any other executions. if (alias_columns_required) { NameSet required_columns_from_prewhere = get_prewhere_columns(); NameSet required_aliases_from_prewhere; /// Set of ALIAS required columns for PREWHERE /// Expression, that contains all raw required columns ASTPtr required_columns_all_expr = std::make_shared(); /// Expression, that contains raw required columns for PREWHERE ASTPtr required_columns_from_prewhere_expr = std::make_shared(); /// Sort out already known required columns between expressions, /// also populate `required_aliases_from_prewhere`. for (const auto & column : required_columns) { ASTPtr column_expr; const auto column_default = storage_columns.getDefault(column); bool is_alias = column_default && column_default->kind == ColumnDefaultKind::Alias; if (is_alias) { auto column_decl = storage_columns.get(column); column_expr = column_default->expression->clone(); // recursive visit for alias to alias replaceAliasColumnsInQuery( column_expr, metadata_snapshot->getColumns(), syntax_analyzer_result->array_join_result_to_source, context); column_expr = addTypeConversionToAST( std::move(column_expr), column_decl.type->getName(), metadata_snapshot->getColumns().getAll(), context); column_expr = setAlias(column_expr, column); } else column_expr = std::make_shared(column); if (required_columns_from_prewhere.contains(column)) { required_columns_from_prewhere_expr->children.emplace_back(std::move(column_expr)); if (is_alias) required_aliases_from_prewhere.insert(column); } else required_columns_all_expr->children.emplace_back(std::move(column_expr)); } /// Columns, which we will get after prewhere and filter executions. NamesAndTypesList required_columns_after_prewhere; NameSet required_columns_after_prewhere_set; /// Collect required columns from prewhere expression actions. if (prewhere_info) { NameSet columns_to_remove(columns_to_remove_after_prewhere.begin(), columns_to_remove_after_prewhere.end()); Block prewhere_actions_result = prewhere_info->prewhere_actions->getResultColumns(); /// Populate required columns with the columns, added by PREWHERE actions and not removed afterwards. /// XXX: looks hacky that we already know which columns after PREWHERE we won't need for sure. for (const auto & column : prewhere_actions_result) { if (prewhere_info->remove_prewhere_column && column.name == prewhere_info->prewhere_column_name) continue; if (columns_to_remove.contains(column.name)) continue; required_columns_all_expr->children.emplace_back(std::make_shared(column.name)); required_columns_after_prewhere.emplace_back(column.name, column.type); } required_columns_after_prewhere_set = collections::map(required_columns_after_prewhere, [](const auto & it) { return it.name; }); } auto syntax_result = TreeRewriter(context).analyze(required_columns_all_expr, required_columns_after_prewhere, storage, storage_snapshot, options.is_create_parameterized_view); alias_actions = ExpressionAnalyzer(required_columns_all_expr, syntax_result, context).getActionsDAG(true); /// The set of required columns could be added as a result of adding an action to calculate ALIAS. required_columns = alias_actions->getRequiredColumns().getNames(); /// Do not remove prewhere filter if it is a column which is used as alias. if (prewhere_info && prewhere_info->remove_prewhere_column) if (required_columns.end() != std::find(required_columns.begin(), required_columns.end(), prewhere_info->prewhere_column_name)) prewhere_info->remove_prewhere_column = false; /// Remove columns which will be added by prewhere. std::erase_if(required_columns, [&](const String & name) { return required_columns_after_prewhere_set.contains(name); }); if (prewhere_info) { /// Don't remove columns which are needed to be aliased. for (const auto & name : required_columns) prewhere_info->prewhere_actions->tryRestoreColumn(name); /// Add physical columns required by prewhere actions. for (const auto & column : required_columns_from_prewhere) if (!required_aliases_from_prewhere.contains(column)) if (required_columns.end() == std::find(required_columns.begin(), required_columns.end(), column)) required_columns.push_back(column); } } const auto & supported_prewhere_columns = storage->supportedPrewhereColumns(); if (supported_prewhere_columns.has_value()) { NameSet required_columns_from_prewhere = get_prewhere_columns(); for (const auto & column_name : required_columns_from_prewhere) { if (!supported_prewhere_columns->contains(column_name)) throw Exception(ErrorCodes::ILLEGAL_PREWHERE, "Storage {} doesn't support PREWHERE for {}", storage->getName(), column_name); } } } void InterpreterSelectQuery::executeFetchColumns(QueryProcessingStage::Enum processing_stage, QueryPlan & query_plan) { auto & query = getSelectQuery(); const Settings & settings = context->getSettingsRef(); /// Optimization for trivial query like SELECT count() FROM table. bool optimize_trivial_count = syntax_analyzer_result->optimize_trivial_count && (settings.max_parallel_replicas <= 1) && !settings.allow_experimental_query_deduplication && !settings.empty_result_for_aggregation_by_empty_set && storage && storage->getName() != "MaterializedMySQL" && !storage->hasLightweightDeletedMask() && query_info.filter_asts.empty() && processing_stage == QueryProcessingStage::FetchColumns && query_analyzer->hasAggregation() && (query_analyzer->aggregates().size() == 1) && typeid_cast(query_analyzer->aggregates()[0].function.get()); if (optimize_trivial_count) { const auto & desc = query_analyzer->aggregates()[0]; const auto & func = desc.function; std::optional num_rows{}; if (!query.prewhere() && !query.where() && !context->getCurrentTransaction()) { num_rows = storage->totalRows(settings); } else // It's possible to optimize count() given only partition predicates { SelectQueryInfo temp_query_info; temp_query_info.query = query_ptr; temp_query_info.syntax_analyzer_result = syntax_analyzer_result; temp_query_info.prepared_sets = query_analyzer->getPreparedSets(); num_rows = storage->totalRowsByPartitionPredicate(temp_query_info, context); } if (num_rows) { const AggregateFunctionCount & agg_count = static_cast(*func); /// We will process it up to "WithMergeableState". std::vector state(agg_count.sizeOfData()); AggregateDataPtr place = state.data(); agg_count.create(place); SCOPE_EXIT_MEMORY_SAFE(agg_count.destroy(place)); agg_count.set(place, *num_rows); auto column = ColumnAggregateFunction::create(func); column->insertFrom(place); Block header = analysis_result.before_aggregation->getResultColumns(); size_t arguments_size = desc.argument_names.size(); DataTypes argument_types(arguments_size); for (size_t j = 0; j < arguments_size; ++j) argument_types[j] = header.getByName(desc.argument_names[j]).type; Block block_with_count{ {std::move(column), std::make_shared(func, argument_types, desc.parameters), desc.column_name}}; auto source = std::make_shared(block_with_count); auto prepared_count = std::make_unique(Pipe(std::move(source))); prepared_count->setStepDescription("Optimized trivial count"); query_plan.addStep(std::move(prepared_count)); from_stage = QueryProcessingStage::WithMergeableState; analysis_result.first_stage = false; return; } } /// Limitation on the number of columns to read. /// It's not applied in 'only_analyze' mode, because the query could be analyzed without removal of unnecessary columns. if (!options.only_analyze && settings.max_columns_to_read && required_columns.size() > settings.max_columns_to_read) throw Exception( ErrorCodes::TOO_MANY_COLUMNS, "Limit for number of columns to read exceeded. Requested: {}, maximum: {}", required_columns.size(), settings.max_columns_to_read); /// General limit for the number of threads. size_t max_threads_execute_query = settings.max_threads; /** With distributed query processing, almost no computations are done in the threads, * but wait and receive data from remote servers. * If we have 20 remote servers, and max_threads = 8, then it would not be very good * connect and ask only 8 servers at a time. * To simultaneously query more remote servers, * instead of max_threads, max_distributed_connections is used. */ bool is_remote = false; if (storage && storage->isRemote()) { is_remote = true; max_threads_execute_query = max_streams = settings.max_distributed_connections; } UInt64 max_block_size = settings.max_block_size; auto [limit_length, limit_offset] = getLimitLengthAndOffset(query, context); auto local_limits = getStorageLimits(*context, options); /** Optimization - if not specified DISTINCT, WHERE, GROUP, HAVING, ORDER, JOIN, LIMIT BY, WITH TIES * but LIMIT is specified, and limit + offset < max_block_size, * then as the block size we will use limit + offset (not to read more from the table than requested), * and also set the number of threads to 1. */ if (!query.distinct && !query.limit_with_ties && !query.prewhere() && !query.where() && query_info.filter_asts.empty() && !query.groupBy() && !query.having() && !query.orderBy() && !query.limitBy() && !query.join() && !query_analyzer->hasAggregation() && !query_analyzer->hasWindow() && query.limitLength() && limit_length <= std::numeric_limits::max() - limit_offset) { if (limit_length + limit_offset < max_block_size) { max_block_size = std::max(1, limit_length + limit_offset); max_threads_execute_query = max_streams = 1; } if (limit_length + limit_offset < local_limits.local_limits.size_limits.max_rows) { query_info.limit = limit_length + limit_offset; } } if (!max_block_size) throw Exception(ErrorCodes::PARAMETER_OUT_OF_BOUND, "Setting 'max_block_size' cannot be zero"); storage_limits.emplace_back(local_limits); /// Initialize the initial data streams to which the query transforms are superimposed. Table or subquery or prepared input? if (query_plan.isInitialized()) { /// Prepared input. } else if (interpreter_subquery) { /// Subquery. ASTPtr subquery = extractTableExpression(query, 0); if (!subquery) throw Exception(ErrorCodes::LOGICAL_ERROR, "Subquery expected"); interpreter_subquery = std::make_unique( subquery, getSubqueryContext(context), options.copy().subquery().noModify(), required_columns); interpreter_subquery->addStorageLimits(storage_limits); if (query_analyzer->hasAggregation()) interpreter_subquery->ignoreWithTotals(); interpreter_subquery->buildQueryPlan(query_plan); query_plan.addInterpreterContext(context); } else if (storage) { /// Table. if (max_streams == 0) max_streams = 1; /// If necessary, we request more sources than the number of threads - to distribute the work evenly over the threads. if (max_streams > 1 && !is_remote) max_streams = static_cast(max_streams * settings.max_streams_to_max_threads_ratio); auto & prewhere_info = analysis_result.prewhere_info; if (prewhere_info) query_info.prewhere_info = prewhere_info; bool optimize_read_in_order = analysis_result.optimize_read_in_order; bool optimize_aggregation_in_order = analysis_result.optimize_aggregation_in_order && !query_analyzer->useGroupingSetKey(); /// Create optimizer with prepared actions. /// Maybe we will need to calc input_order_info later, e.g. while reading from StorageMerge. if ((optimize_read_in_order || optimize_aggregation_in_order) && (!query_info.projection || query_info.projection->complete)) { if (optimize_read_in_order) { if (query_info.projection) { query_info.projection->order_optimizer = std::make_shared( // TODO Do we need a projection variant for this field? query, analysis_result.order_by_elements_actions, getSortDescription(query, context), query_info.syntax_analyzer_result); } else { query_info.order_optimizer = std::make_shared( query, analysis_result.order_by_elements_actions, getSortDescription(query, context), query_info.syntax_analyzer_result); } } else if (optimize_aggregation_in_order) { if (query_info.projection) { query_info.projection->order_optimizer = std::make_shared( query, query_info.projection->group_by_elements_actions, query_info.projection->group_by_elements_order_descr, query_info.syntax_analyzer_result); } else { query_info.order_optimizer = std::make_shared( query, analysis_result.group_by_elements_actions, getSortDescriptionFromGroupBy(query), query_info.syntax_analyzer_result); } } /// If we don't have filtration, we can pushdown limit to reading stage for optimizations. UInt64 limit = (query.hasFiltration() || query.groupBy()) ? 0 : getLimitForSorting(query, context); if (query_info.projection) query_info.projection->input_order_info = query_info.projection->order_optimizer->getInputOrder(query_info.projection->desc->metadata, context, limit); else query_info.input_order_info = query_info.order_optimizer->getInputOrder(metadata_snapshot, context, limit); } query_info.storage_limits = std::make_shared(storage_limits); query_info.settings_limit_offset_done = options.settings_limit_offset_done; storage->read(query_plan, required_columns, storage_snapshot, query_info, context, processing_stage, max_block_size, max_streams); if (context->hasQueryContext() && !options.is_internal) { const String view_name{}; auto local_storage_id = storage->getStorageID(); context->getQueryContext()->addQueryAccessInfo( backQuoteIfNeed(local_storage_id.getDatabaseName()), local_storage_id.getFullTableName(), required_columns, query_info.projection ? query_info.projection->desc->name : "", view_name); } /// Create step which reads from empty source if storage has no data. if (!query_plan.isInitialized()) { auto header = storage_snapshot->getSampleBlockForColumns(required_columns); addEmptySourceToQueryPlan(query_plan, header, query_info, context); } } else throw Exception(ErrorCodes::LOGICAL_ERROR, "Logical error in InterpreterSelectQuery: nowhere to read"); /// Specify the number of threads only if it wasn't specified in storage. /// /// But in case of remote query and prefer_localhost_replica=1 (default) /// The inner local query (that is done in the same process, without /// network interaction), it will setMaxThreads earlier and distributed /// query will not update it. if (!query_plan.getMaxThreads() || is_remote) query_plan.setMaxThreads(max_threads_execute_query); /// Aliases in table declaration. if (processing_stage == QueryProcessingStage::FetchColumns && alias_actions) { auto table_aliases = std::make_unique(query_plan.getCurrentDataStream(), alias_actions); table_aliases->setStepDescription("Add table aliases"); query_plan.addStep(std::move(table_aliases)); } } void InterpreterSelectQuery::executeWhere(QueryPlan & query_plan, const ActionsDAGPtr & expression, bool remove_filter) { auto where_step = std::make_unique( query_plan.getCurrentDataStream(), expression, getSelectQuery().where()->getColumnName(), remove_filter); where_step->setStepDescription("WHERE"); query_plan.addStep(std::move(where_step)); } static Aggregator::Params getAggregatorParams( const ASTPtr & query_ptr, const SelectQueryExpressionAnalyzer & query_analyzer, const Context & context, const Names & keys, const AggregateDescriptions & aggregates, bool overflow_row, const Settings & settings, size_t group_by_two_level_threshold, size_t group_by_two_level_threshold_bytes) { const auto stats_collecting_params = Aggregator::Params::StatsCollectingParams( query_ptr, settings.collect_hash_table_stats_during_aggregation, settings.max_entries_for_hash_table_stats, settings.max_size_to_preallocate_for_aggregation); return Aggregator::Params { keys, aggregates, overflow_row, settings.max_rows_to_group_by, settings.group_by_overflow_mode, group_by_two_level_threshold, group_by_two_level_threshold_bytes, settings.max_bytes_before_external_group_by, settings.empty_result_for_aggregation_by_empty_set || (settings.empty_result_for_aggregation_by_constant_keys_on_empty_set && keys.empty() && query_analyzer.hasConstAggregationKeys()), context.getTempDataOnDisk(), settings.max_threads, settings.min_free_disk_space_for_temporary_data, settings.compile_aggregate_expressions, settings.min_count_to_compile_aggregate_expression, settings.max_block_size, settings.enable_software_prefetch_in_aggregation, /* only_merge */ false, stats_collecting_params }; } static GroupingSetsParamsList getAggregatorGroupingSetsParams(const SelectQueryExpressionAnalyzer & query_analyzer, const Names & all_keys) { GroupingSetsParamsList result; if (query_analyzer.useGroupingSetKey()) { auto const & aggregation_keys_list = query_analyzer.aggregationKeysList(); for (const auto & aggregation_keys : aggregation_keys_list) { NameSet keys; for (const auto & key : aggregation_keys) keys.insert(key.name); Names missing_keys; for (const auto & key : all_keys) if (!keys.contains(key)) missing_keys.push_back(key); result.emplace_back(aggregation_keys.getNames(), std::move(missing_keys)); } } return result; } void InterpreterSelectQuery::executeAggregation(QueryPlan & query_plan, const ActionsDAGPtr & expression, bool overflow_row, bool final, InputOrderInfoPtr group_by_info) { auto expression_before_aggregation = std::make_unique(query_plan.getCurrentDataStream(), expression); expression_before_aggregation->setStepDescription("Before GROUP BY"); query_plan.addStep(std::move(expression_before_aggregation)); if (options.is_projection_query) return; AggregateDescriptions aggregates = query_analyzer->aggregates(); const Settings & settings = context->getSettingsRef(); const auto & keys = query_analyzer->aggregationKeys().getNames(); auto aggregator_params = getAggregatorParams( query_ptr, *query_analyzer, *context, keys, aggregates, overflow_row, settings, settings.group_by_two_level_threshold, settings.group_by_two_level_threshold_bytes); auto grouping_sets_params = getAggregatorGroupingSetsParams(*query_analyzer, keys); SortDescription group_by_sort_description; SortDescription sort_description_for_merging; if (group_by_info && settings.optimize_aggregation_in_order && !query_analyzer->useGroupingSetKey()) { group_by_sort_description = getSortDescriptionFromGroupBy(getSelectQuery()); sort_description_for_merging = group_by_info->sort_description_for_merging; } else group_by_info = nullptr; if (!group_by_info && settings.force_aggregation_in_order) { group_by_sort_description = getSortDescriptionFromGroupBy(getSelectQuery()); sort_description_for_merging = group_by_sort_description; } auto merge_threads = max_streams; auto temporary_data_merge_threads = settings.aggregation_memory_efficient_merge_threads ? static_cast(settings.aggregation_memory_efficient_merge_threads) : static_cast(settings.max_threads); bool storage_has_evenly_distributed_read = storage && storage->hasEvenlyDistributedRead(); const bool should_produce_results_in_order_of_bucket_number = options.to_stage == QueryProcessingStage::WithMergeableState && (settings.distributed_aggregation_memory_efficient || settings.enable_memory_bound_merging_of_aggregation_results); auto aggregating_step = std::make_unique( query_plan.getCurrentDataStream(), std::move(aggregator_params), std::move(grouping_sets_params), final, settings.max_block_size, settings.aggregation_in_order_max_block_bytes, merge_threads, temporary_data_merge_threads, storage_has_evenly_distributed_read, settings.group_by_use_nulls, std::move(sort_description_for_merging), std::move(group_by_sort_description), should_produce_results_in_order_of_bucket_number, settings.enable_memory_bound_merging_of_aggregation_results, !group_by_info && settings.force_aggregation_in_order); query_plan.addStep(std::move(aggregating_step)); } void InterpreterSelectQuery::executeMergeAggregated(QueryPlan & query_plan, bool overflow_row, bool final, bool has_grouping_sets) { /// If aggregate projection was chosen for table, avoid adding MergeAggregated. /// It is already added by storage (because of performance issues). /// TODO: We should probably add another one processing stage for storage? /// WithMergeableStateAfterAggregation is not ok because, e.g., it skips sorting after aggregation. if (query_info.projection && query_info.projection->desc->type == ProjectionDescription::Type::Aggregate) return; const Settings & settings = context->getSettingsRef(); /// Used to determine if we should use memory bound merging strategy. auto group_by_sort_description = !query_analyzer->useGroupingSetKey() ? getSortDescriptionFromGroupBy(getSelectQuery()) : SortDescription{}; const bool should_produce_results_in_order_of_bucket_number = options.to_stage == QueryProcessingStage::WithMergeableState && (settings.distributed_aggregation_memory_efficient || settings.enable_memory_bound_merging_of_aggregation_results); const bool parallel_replicas_from_merge_tree = storage->isMergeTree() && context->canUseParallelReplicasOnInitiator(); executeMergeAggregatedImpl( query_plan, overflow_row, final, storage && (storage->isRemote() || parallel_replicas_from_merge_tree), has_grouping_sets, context->getSettingsRef(), query_analyzer->aggregationKeys(), query_analyzer->aggregates(), should_produce_results_in_order_of_bucket_number, std::move(group_by_sort_description)); } void InterpreterSelectQuery::executeHaving(QueryPlan & query_plan, const ActionsDAGPtr & expression, bool remove_filter) { auto having_step = std::make_unique(query_plan.getCurrentDataStream(), expression, getSelectQuery().having()->getColumnName(), remove_filter); having_step->setStepDescription("HAVING"); query_plan.addStep(std::move(having_step)); } void InterpreterSelectQuery::executeTotalsAndHaving( QueryPlan & query_plan, bool has_having, const ActionsDAGPtr & expression, bool remove_filter, bool overflow_row, bool final) { const Settings & settings = context->getSettingsRef(); auto totals_having_step = std::make_unique( query_plan.getCurrentDataStream(), query_analyzer->aggregates(), overflow_row, expression, has_having ? getSelectQuery().having()->getColumnName() : "", remove_filter, settings.totals_mode, settings.totals_auto_threshold, final); query_plan.addStep(std::move(totals_having_step)); } void InterpreterSelectQuery::executeRollupOrCube(QueryPlan & query_plan, Modificator modificator) { const Settings & settings = context->getSettingsRef(); const auto & keys = query_analyzer->aggregationKeys().getNames(); // Arguments will not be present in Rollup / Cube input header and they don't actually needed 'cause these steps will work with AggregateFunctionState-s anyway. auto aggregates = query_analyzer->aggregates(); for (auto & aggregate : aggregates) aggregate.argument_names.clear(); auto params = getAggregatorParams(query_ptr, *query_analyzer, *context, keys, aggregates, false, settings, 0, 0); const bool final = true; QueryPlanStepPtr step; if (modificator == Modificator::ROLLUP) step = std::make_unique(query_plan.getCurrentDataStream(), std::move(params), final, settings.group_by_use_nulls); else if (modificator == Modificator::CUBE) step = std::make_unique(query_plan.getCurrentDataStream(), std::move(params), final, settings.group_by_use_nulls); query_plan.addStep(std::move(step)); } void InterpreterSelectQuery::executeExpression(QueryPlan & query_plan, const ActionsDAGPtr & expression, const std::string & description) { if (!expression) return; auto expression_step = std::make_unique(query_plan.getCurrentDataStream(), expression); expression_step->setStepDescription(description); query_plan.addStep(std::move(expression_step)); } static bool windowDescriptionComparator(const WindowDescription * _left, const WindowDescription * _right) { const auto & left = _left->full_sort_description; const auto & right = _right->full_sort_description; for (size_t i = 0; i < std::min(left.size(), right.size()); ++i) { if (left[i].column_name < right[i].column_name) return true; else if (left[i].column_name > right[i].column_name) return false; else if (left[i].direction < right[i].direction) return true; else if (left[i].direction > right[i].direction) return false; else if (left[i].nulls_direction < right[i].nulls_direction) return true; else if (left[i].nulls_direction > right[i].nulls_direction) return false; assert(left[i] == right[i]); } // Note that we check the length last, because we want to put together the // sort orders that have common prefix but different length. return left.size() > right.size(); } static bool sortIsPrefix(const WindowDescription & _prefix, const WindowDescription & _full) { const auto & prefix = _prefix.full_sort_description; const auto & full = _full.full_sort_description; if (prefix.size() > full.size()) return false; for (size_t i = 0; i < prefix.size(); ++i) { if (full[i] != prefix[i]) return false; } return true; } void InterpreterSelectQuery::executeWindow(QueryPlan & query_plan) { // Try to sort windows in such an order that the window with the longest // sort description goes first, and all window that use its prefixes follow. std::vector windows_sorted; for (const auto & [_, window] : query_analyzer->windowDescriptions()) windows_sorted.push_back(&window); ::sort(windows_sorted.begin(), windows_sorted.end(), windowDescriptionComparator); const Settings & settings = context->getSettingsRef(); for (size_t i = 0; i < windows_sorted.size(); ++i) { const auto & window = *windows_sorted[i]; // We don't need to sort again if the input from previous window already // has suitable sorting. Also don't create sort steps when there are no // columns to sort by, because the sort nodes are confused by this. It // happens in case of `over ()`. if (!window.full_sort_description.empty() && (i == 0 || !sortIsPrefix(window, *windows_sorted[i - 1]))) { SortingStep::Settings sort_settings(*context); auto sorting_step = std::make_unique( query_plan.getCurrentDataStream(), window.full_sort_description, 0 /* LIMIT */, sort_settings, settings.optimize_sorting_by_input_stream_properties); sorting_step->setStepDescription("Sorting for window '" + window.window_name + "'"); query_plan.addStep(std::move(sorting_step)); } auto window_step = std::make_unique(query_plan.getCurrentDataStream(), window, window.window_functions); window_step->setStepDescription("Window step for window '" + window.window_name + "'"); query_plan.addStep(std::move(window_step)); } } void InterpreterSelectQuery::executeOrderOptimized(QueryPlan & query_plan, InputOrderInfoPtr input_sorting_info, UInt64 limit, SortDescription & output_order_descr) { const Settings & settings = context->getSettingsRef(); auto finish_sorting_step = std::make_unique( query_plan.getCurrentDataStream(), input_sorting_info->sort_description_for_merging, output_order_descr, settings.max_block_size, limit); query_plan.addStep(std::move(finish_sorting_step)); } void InterpreterSelectQuery::executeOrder(QueryPlan & query_plan, InputOrderInfoPtr input_sorting_info) { auto & query = getSelectQuery(); SortDescription output_order_descr = getSortDescription(query, context); UInt64 limit = getLimitForSorting(query, context); if (input_sorting_info) { /* Case of sorting with optimization using sorting key. * We have several threads, each of them reads batch of parts in direct * or reverse order of sorting key using one input stream per part * and then merge them into one sorted stream. * At this stage we merge per-thread streams into one. */ executeOrderOptimized(query_plan, input_sorting_info, limit, output_order_descr); return; } const Settings & settings = context->getSettingsRef(); SortingStep::Settings sort_settings(*context); /// Merge the sorted blocks. auto sorting_step = std::make_unique( query_plan.getCurrentDataStream(), output_order_descr, limit, sort_settings, settings.optimize_sorting_by_input_stream_properties); sorting_step->setStepDescription("Sorting for ORDER BY"); query_plan.addStep(std::move(sorting_step)); } void InterpreterSelectQuery::executeMergeSorted(QueryPlan & query_plan, const std::string & description) { const auto & query = getSelectQuery(); SortDescription sort_description = getSortDescription(query, context); const UInt64 limit = getLimitForSorting(query, context); const auto max_block_size = context->getSettingsRef().max_block_size; const auto exact_rows_before_limit = context->getSettingsRef().exact_rows_before_limit; auto merging_sorted = std::make_unique( query_plan.getCurrentDataStream(), std::move(sort_description), max_block_size, limit, exact_rows_before_limit); merging_sorted->setStepDescription("Merge sorted streams " + description); query_plan.addStep(std::move(merging_sorted)); } void InterpreterSelectQuery::executeProjection(QueryPlan & query_plan, const ActionsDAGPtr & expression) { auto projection_step = std::make_unique(query_plan.getCurrentDataStream(), expression); projection_step->setStepDescription("Projection"); query_plan.addStep(std::move(projection_step)); } void InterpreterSelectQuery::executeDistinct(QueryPlan & query_plan, bool before_order, Names columns, bool pre_distinct) { auto & query = getSelectQuery(); if (query.distinct) { const Settings & settings = context->getSettingsRef(); UInt64 limit_for_distinct = 0; /// If after this stage of DISTINCT, /// (1) ORDER BY is not executed /// (2) there is no LIMIT BY (todo: we can check if DISTINCT and LIMIT BY expressions are match) /// then you can get no more than limit_length + limit_offset of different rows. if ((!query.orderBy() || !before_order) && !query.limitBy()) { auto [limit_length, limit_offset] = getLimitLengthAndOffset(query, context); if (limit_length <= std::numeric_limits::max() - limit_offset) limit_for_distinct = limit_length + limit_offset; } SizeLimits limits(settings.max_rows_in_distinct, settings.max_bytes_in_distinct, settings.distinct_overflow_mode); auto distinct_step = std::make_unique( query_plan.getCurrentDataStream(), limits, limit_for_distinct, columns, pre_distinct, settings.optimize_distinct_in_order); if (pre_distinct) distinct_step->setStepDescription("Preliminary DISTINCT"); query_plan.addStep(std::move(distinct_step)); } } /// Preliminary LIMIT - is used in every source, if there are several sources, before they are combined. void InterpreterSelectQuery::executePreLimit(QueryPlan & query_plan, bool do_not_skip_offset) { auto & query = getSelectQuery(); /// If there is LIMIT if (query.limitLength()) { auto [limit_length, limit_offset] = getLimitLengthAndOffset(query, context); if (do_not_skip_offset) { if (limit_length > std::numeric_limits::max() - limit_offset) return; limit_length += limit_offset; limit_offset = 0; } const Settings & settings = context->getSettingsRef(); auto limit = std::make_unique(query_plan.getCurrentDataStream(), limit_length, limit_offset, settings.exact_rows_before_limit); if (do_not_skip_offset) limit->setStepDescription("preliminary LIMIT (with OFFSET)"); else limit->setStepDescription("preliminary LIMIT (without OFFSET)"); query_plan.addStep(std::move(limit)); } } void InterpreterSelectQuery::executeLimitBy(QueryPlan & query_plan) { auto & query = getSelectQuery(); if (!query.limitByLength() || !query.limitBy()) return; Names columns; for (const auto & elem : query.limitBy()->children) columns.emplace_back(elem->getColumnName()); UInt64 length = getLimitUIntValue(query.limitByLength(), context, "LIMIT"); UInt64 offset = (query.limitByOffset() ? getLimitUIntValue(query.limitByOffset(), context, "OFFSET") : 0); auto limit_by = std::make_unique(query_plan.getCurrentDataStream(), length, offset, columns); query_plan.addStep(std::move(limit_by)); } void InterpreterSelectQuery::executeWithFill(QueryPlan & query_plan) { auto & query = getSelectQuery(); if (query.orderBy()) { SortDescription order_descr = getSortDescription(query, context); SortDescription fill_descr; for (auto & desc : order_descr) { if (desc.with_fill) fill_descr.push_back(desc); } if (fill_descr.empty()) return; InterpolateDescriptionPtr interpolate_descr = getInterpolateDescription(query, source_header, result_header, syntax_analyzer_result->aliases, context); auto filling_step = std::make_unique(query_plan.getCurrentDataStream(), std::move(fill_descr), interpolate_descr); query_plan.addStep(std::move(filling_step)); } } void InterpreterSelectQuery::executeLimit(QueryPlan & query_plan) { auto & query = getSelectQuery(); /// If there is LIMIT if (query.limitLength()) { /** Rare case: * if there is no WITH TOTALS and there is a subquery in FROM, and there is WITH TOTALS on one of the levels, * then when using LIMIT, you should read the data to the end, rather than cancel the query earlier, * because if you cancel the query, we will not get `totals` data from the remote server. * * Another case: * if there is WITH TOTALS and there is no ORDER BY, then read the data to the end, * otherwise TOTALS is counted according to incomplete data. */ const Settings & settings = context->getSettingsRef(); bool always_read_till_end = settings.exact_rows_before_limit; if (query.group_by_with_totals && !query.orderBy()) always_read_till_end = true; if (!query.group_by_with_totals && hasWithTotalsInAnySubqueryInFromClause(query)) always_read_till_end = true; UInt64 limit_length; UInt64 limit_offset; std::tie(limit_length, limit_offset) = getLimitLengthAndOffset(query, context); SortDescription order_descr; if (query.limit_with_ties) { if (!query.orderBy()) throw Exception(ErrorCodes::LOGICAL_ERROR, "LIMIT WITH TIES without ORDER BY"); order_descr = getSortDescription(query, context); } auto limit = std::make_unique( query_plan.getCurrentDataStream(), limit_length, limit_offset, always_read_till_end, query.limit_with_ties, order_descr); if (query.limit_with_ties) limit->setStepDescription("LIMIT WITH TIES"); query_plan.addStep(std::move(limit)); } } void InterpreterSelectQuery::executeOffset(QueryPlan & query_plan) { auto & query = getSelectQuery(); /// If there is not a LIMIT but an offset if (!query.limitLength() && query.limitOffset()) { UInt64 limit_length; UInt64 limit_offset; std::tie(limit_length, limit_offset) = getLimitLengthAndOffset(query, context); auto offsets_step = std::make_unique(query_plan.getCurrentDataStream(), limit_offset); query_plan.addStep(std::move(offsets_step)); } } void InterpreterSelectQuery::executeExtremes(QueryPlan & query_plan) { if (!context->getSettingsRef().extremes) return; auto extremes_step = std::make_unique(query_plan.getCurrentDataStream()); query_plan.addStep(std::move(extremes_step)); } void InterpreterSelectQuery::executeSubqueriesInSetsAndJoins(QueryPlan & query_plan) { addCreatingSetsStep(query_plan, prepared_sets, context); } void InterpreterSelectQuery::ignoreWithTotals() { getSelectQuery().group_by_with_totals = false; } bool InterpreterSelectQuery::autoFinalOnQuery(ASTSelectQuery & query) { // query.tables() is required because not all queries have tables in it, it could be a function. bool is_auto_final_setting_on = context->getSettingsRef().final; bool is_final_supported = storage && storage->supportsFinal() && !storage->isRemote() && query.tables(); bool is_query_already_final = query.final(); return is_auto_final_setting_on && !is_query_already_final && is_final_supported; } void InterpreterSelectQuery::initSettings() { auto & query = getSelectQuery(); if (query.settings()) InterpreterSetQuery(query.settings(), context).executeForCurrentContext(); auto & client_info = context->getClientInfo(); auto min_major = DBMS_MIN_MAJOR_VERSION_WITH_CURRENT_AGGREGATION_VARIANT_SELECTION_METHOD; auto min_minor = DBMS_MIN_MINOR_VERSION_WITH_CURRENT_AGGREGATION_VARIANT_SELECTION_METHOD; if (client_info.query_kind == ClientInfo::QueryKind::SECONDARY_QUERY && std::forward_as_tuple(client_info.connection_client_version_major, client_info.connection_client_version_minor) < std::forward_as_tuple(min_major, min_minor)) { /// Disable two-level aggregation due to version incompatibility. context->setSetting("group_by_two_level_threshold", Field(0)); context->setSetting("group_by_two_level_threshold_bytes", Field(0)); } } }