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ClickHouse/src/Interpreters/InterpreterSelectQuery.cpp

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#include <DataTypes/DataTypeAggregateFunction.h>
#include <DataTypes/DataTypeInterval.h>
#include <Parsers/ASTFunction.h>
#include <Parsers/ASTIdentifier.h>
#include <Parsers/ASTLiteral.h>
#include <Parsers/ASTOrderByElement.h>
#include <Parsers/ASTSelectWithUnionQuery.h>
#include <Parsers/ASTSelectIntersectExceptQuery.h>
#include <Parsers/ASTTablesInSelectQuery.h>
#include <Parsers/ExpressionListParsers.h>
#include <Parsers/parseQuery.h>
#include <Access/Common/AccessFlags.h>
#include <Access/ContextAccess.h>
#include <AggregateFunctions/AggregateFunctionCount.h>
#include <Interpreters/ApplyWithAliasVisitor.h>
#include <Interpreters/ApplyWithSubqueryVisitor.h>
#include <Interpreters/InterpreterSelectQuery.h>
#include <Interpreters/InterpreterSelectWithUnionQuery.h>
#include <Interpreters/InterpreterSetQuery.h>
#include <Interpreters/evaluateConstantExpression.h>
#include <Interpreters/convertFieldToType.h>
#include <Interpreters/addTypeConversionToAST.h>
#include <Interpreters/ExpressionAnalyzer.h>
#include <Interpreters/getTableExpressions.h>
#include <Interpreters/JoinToSubqueryTransformVisitor.h>
#include <Interpreters/CrossToInnerJoinVisitor.h>
#include <Interpreters/TableJoin.h>
#include <Interpreters/JoinedTables.h>
#include <Interpreters/OpenTelemetrySpanLog.h>
#include <Interpreters/QueryAliasesVisitor.h>
#include <Interpreters/replaceAliasColumnsInQuery.h>
#include <QueryPipeline/Pipe.h>
#include <Processors/QueryPlan/AggregatingStep.h>
#include <Processors/QueryPlan/ArrayJoinStep.h>
#include <Processors/QueryPlan/CreatingSetsStep.h>
#include <Processors/QueryPlan/CubeStep.h>
#include <Processors/QueryPlan/DistinctStep.h>
#include <Processors/QueryPlan/ExpressionStep.h>
#include <Processors/QueryPlan/ExtremesStep.h>
#include <Processors/QueryPlan/FillingStep.h>
#include <Processors/QueryPlan/FilterStep.h>
#include <Processors/QueryPlan/JoinStep.h>
#include <Processors/QueryPlan/LimitByStep.h>
#include <Processors/QueryPlan/LimitStep.h>
#include <Processors/QueryPlan/SortingStep.h>
#include <Processors/QueryPlan/MergingAggregatedStep.h>
#include <Processors/QueryPlan/OffsetStep.h>
#include <Processors/QueryPlan/QueryPlan.h>
#include <Processors/QueryPlan/ReadFromPreparedSource.h>
#include <Processors/QueryPlan/ReadNothingStep.h>
#include <Processors/QueryPlan/RollupStep.h>
#include <Processors/QueryPlan/SettingQuotaAndLimitsStep.h>
#include <Processors/QueryPlan/TotalsHavingStep.h>
#include <Processors/QueryPlan/WindowStep.h>
#include <Processors/QueryPlan/Optimizations/QueryPlanOptimizationSettings.h>
#include <Processors/Sources/NullSource.h>
#include <Processors/Sources/SourceFromSingleChunk.h>
#include <Processors/Transforms/AggregatingTransform.h>
#include <Processors/Transforms/ExpressionTransform.h>
#include <Processors/Transforms/FilterTransform.h>
#include <Storages/IStorage.h>
#include <Storages/MergeTree/MergeTreeWhereOptimizer.h>
#include <Storages/StorageValues.h>
#include <Storages/StorageView.h>
#include <Functions/IFunction.h>
#include <Core/Field.h>
#include <Core/ProtocolDefines.h>
#include <base/types.h>
#include <base/sort.h>
#include <Columns/Collator.h>
#include <Common/FieldVisitorsAccurateComparison.h>
#include <Common/FieldVisitorToString.h>
#include <Common/typeid_cast.h>
#include <Common/checkStackSize.h>
#include <base/map.h>
#include <base/scope_guard_safe.h>
#include <memory>
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;
}
/// Assumes `storage` is set and the table filter (row-level security) is not empty.
String InterpreterSelectQuery::generateFilterActions(ActionsDAGPtr & actions, const Names & prerequisite_columns) const
{
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<ASTSelectQuery>();
auto * select_ast = query_ast->as<ASTSelectQuery>();
select_ast->setExpression(ASTSelectQuery::Expression::SELECT, std::make_shared<ASTExpressionList>());
auto expr_list = select_ast->select();
/// The first column is our filter expression.
/// the row_policy_filter 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->clone());
/// Keep columns that are required after the filter actions.
for (const auto & column_str : prerequisite_columns)
{
ParserExpression expr_parser;
expr_list->children.push_back(parseQuery(expr_parser, column_str, 0, context->getSettingsRef().max_parser_depth));
}
select_ast->setExpression(ASTSelectQuery::Expression::TABLES, std::make_shared<ASTTablesInSelectQuery>());
auto tables = select_ast->tables();
auto tables_elem = std::make_shared<ASTTablesInSelectQueryElement>();
auto table_expr = std::make_shared<ASTTableExpression>();
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<ASTTableIdentifier>(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);
actions = analyzer.simpleSelectActions();
auto column_name = expr_list->children.at(0)->getColumnName();
actions->removeUnusedActions(NameSet{column_name});
actions->projectInput(false);
for (const auto * node : actions->getInputs())
actions->getIndex().push_back(node);
return column_name;
}
InterpreterSelectQuery::InterpreterSelectQuery(
const ASTPtr & query_ptr_,
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_,
ContextPtr context_,
const SelectQueryOptions & options_,
PreparedSets prepared_sets_)
: InterpreterSelectQuery(query_ptr_, context_, std::nullopt, nullptr, options_, {}, {}, std::move(prepared_sets_))
{
}
InterpreterSelectQuery::InterpreterSelectQuery(
const ASTPtr & query_ptr_,
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_,
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() = default;
/** 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.
*/
static ContextPtr getSubqueryContext(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;
}
static void rewriteMultipleJoins(ASTPtr & query, const TablesWithColumns & tables, const String & database, const Settings & settings)
{
ASTSelectQuery & select = query->as<ASTSelectQuery &>();
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 = settings.cross_to_inner_join_rewrite;
CrossToInnerJoinVisitor(cross_to_inner).visit(query);
JoinToSubqueryTransformVisitor::Data join_to_subs_data{tables, aliases};
JoinToSubqueryTransformVisitor(join_to_subs_data).visit(query);
}
/// Checks that the current user has the SELECT privilege.
static void checkAccessRightsForSelect(
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());
}
/// Returns true if we should ignore quotas and limits for a specified table in the system database.
static bool shouldIgnoreQuotaAndLimits(const StorageID & table_id)
{
if (table_id.database_name == DatabaseCatalog::SYSTEM_DATABASE)
{
static const boost::container::flat_set<String> 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_,
ContextPtr context_,
std::optional<Pipe> input_pipe_,
const StoragePtr & storage_,
const SelectQueryOptions & options_,
const Names & required_result_column_names,
const StorageMetadataPtr & metadata_snapshot_,
PreparedSets 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(std::move(prepared_sets_))
{
checkStackSize();
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("Too deep subqueries. Maximum: " + settings.max_subquery_depth.toString(),
ErrorCodes::TOO_DEEP_SUBQUERIES);
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();
JoinedTables joined_tables(getSubqueryContext(context), getSelectQuery(), options.with_all_cols);
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);
}
if (has_input || !joined_tables.resolveTables())
joined_tables.makeFakeTable(storage, metadata_snapshot, source_header);
/// 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<const StorageValues &>(*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;
}
}
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<TableJoin> 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<StorageView *>(storage.get());
/// Reuse already built sets for multiple passes of analysis
SubqueriesForSets subquery_for_sets;
auto analyze = [&] (bool try_move_to_prewhere)
{
/// Allow push down and other optimizations for VIEW: replace with subquery and rewrite it.
ASTPtr view_table;
if (view)
view->replaceWithSubquery(getSelectQuery(), view_table, metadata_snapshot);
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.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())
{
/// 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<std::string, UInt64> 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;
MergeTreeWhereOptimizer{
current_info,
context,
std::move(column_compressed_sizes),
metadata_snapshot,
syntax_analyzer_result->requiredSourceColumns(),
log};
}
}
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<SelectQueryExpressionAnalyzer>(
query_ptr,
syntax_analyzer_result,
context,
metadata_snapshot,
NameSet(required_result_column_names.begin(), required_result_column_names.end()),
!options.only_analyze,
options,
std::move(subquery_for_sets),
std::move(prepared_sets));
if (!options.only_analyze)
{
if (query.sampleSize() && (input_pipe || !storage || !storage->supportsSampling()))
throw Exception("Illegal SAMPLE: table doesn't support sampling", ErrorCodes::SAMPLING_NOT_SUPPORTED);
if (query.final() && (input_pipe || !storage || !storage->supportsFinal()))
throw Exception(
(!input_pipe && storage) ? "Storage " + storage->getName() + " doesn't support FINAL" : "Illegal FINAL",
ErrorCodes::ILLEGAL_FINAL);
if (query.prewhere() && (input_pipe || !storage || !storage->supportsPrewhere()))
throw Exception(
(!input_pipe && storage) ? "Storage " + storage->getName() + " doesn't support PREWHERE" : "Illegal PREWHERE",
ErrorCodes::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)
{
/// Fix source_header for filter actions.
if (row_policy_filter)
{
filter_info = std::make_shared<FilterDAGInfo>();
filter_info->column_name = generateFilterActions(filter_info->actions, required_columns);
auto required_columns_from_filter = filter_info->actions->getRequiredColumns();
for (const auto & column : required_columns_from_filter)
{
if (required_columns.end() == std::find(required_columns.begin(), required_columns.end(), column.name))
required_columns.push_back(column.name);
}
}
source_header = storage_snapshot->getSampleBlockForColumns(required_columns);
}
/// Calculate structure of the result.
result_header = getSampleBlockImpl();
};
analyze(shouldMoveToPrewhere());
bool need_analyze_again = false;
if (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<ASTLiteral>(0u));
need_analyze_again = true;
}
if (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<ASTLiteral>(0u));
need_analyze_again = true;
}
if (need_analyze_again)
{
LOG_TRACE(log, "Running 'analyze' second time");
/// Reuse already built sets for multiple passes of analysis
subquery_for_sets = std::move(query_analyzer->getSubqueriesForSets());
prepared_sets = query_info.sets.empty() ? query_analyzer->getPreparedSets() : query_info.sets;
/// 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<ExpressionStep>(query_plan.getCurrentDataStream(), convert_actions_dag);
query_plan.addStep(std::move(converting));
}
}
BlockIO InterpreterSelectQuery::execute()
{
BlockIO res;
QueryPlan query_plan;
buildQueryPlan(query_plan);
res.pipeline = QueryPipelineBuilder::getPipeline(std::move(*query_plan.buildQueryPipeline(
QueryPlanOptimizationSettings::fromContext(context), BuildQueryPipelineSettings::fromContext(context))));
return res;
}
Block InterpreterSelectQuery::getSampleBlockImpl()
{
query_info.query = query_ptr;
query_info.has_window = query_analyzer->hasWindow();
if (storage && !options.only_analyze)
{
auto & query = getSelectQuery();
query_analyzer->makeSetsForIndex(query.where());
query_analyzer->makeSetsForIndex(query.prewhere());
query_info.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, 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;
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<DataTypeAggregateFunction>(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 Field getWithFillFieldValue(const ASTPtr & node, ContextPtr context)
{
auto [field, type] = evaluateConstantExpression(node, context);
if (!isColumnedAsNumber(type))
throw Exception("Illegal type " + type->getName() + " of WITH FILL expression, must be numeric type", ErrorCodes::INVALID_WITH_FILL_EXPRESSION);
return field;
}
static std::pair<Field, std::optional<IntervalKind>> getWithFillStep(const ASTPtr & node, ContextPtr context)
{
auto [field, type] = evaluateConstantExpression(node, context);
if (const auto * type_interval = typeid_cast<const DataTypeInterval *>(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("Illegal type " + type->getName() + " of WITH FILL expression, must be numeric type", ErrorCodes::INVALID_WITH_FILL_EXPRESSION);
}
static FillColumnDescription getWithFillDescription(const ASTOrderByElement & order_by_elem, ContextPtr context)
{
FillColumnDescription descr;
if (order_by_elem.fill_from)
descr.fill_from = getWithFillFieldValue(order_by_elem.fill_from, context);
if (order_by_elem.fill_to)
descr.fill_to = 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("WITH FILL STEP value cannot be zero", ErrorCodes::INVALID_WITH_FILL_EXPRESSION);
if (order_by_elem.direction == 1)
{
if (applyVisitor(FieldVisitorAccurateLess(), descr.fill_step, Field{0}))
throw Exception("WITH FILL STEP value cannot be negative for sorting in ascending direction",
ErrorCodes::INVALID_WITH_FILL_EXPRESSION);
if (!descr.fill_from.isNull() && !descr.fill_to.isNull() &&
applyVisitor(FieldVisitorAccurateLess(), descr.fill_to, descr.fill_from))
{
throw Exception("WITH FILL TO value cannot be less than FROM value for sorting in ascending direction",
ErrorCodes::INVALID_WITH_FILL_EXPRESSION);
}
}
else
{
if (applyVisitor(FieldVisitorAccurateLess(), Field{0}, descr.fill_step))
throw Exception("WITH FILL STEP value cannot be positive for sorting in descending direction",
ErrorCodes::INVALID_WITH_FILL_EXPRESSION);
if (!descr.fill_from.isNull() && !descr.fill_to.isNull() &&
applyVisitor(FieldVisitorAccurateLess(), descr.fill_from, descr.fill_to))
{
throw Exception("WITH FILL FROM value cannot be less than TO value for sorting in descending direction",
ErrorCodes::INVALID_WITH_FILL_EXPRESSION);
}
}
return descr;
}
static SortDescription getSortDescription(const ASTSelectQuery & query, ContextPtr context)
{
SortDescription order_descr;
order_descr.reserve(query.orderBy()->children.size());
for (const auto & elem : query.orderBy()->children)
{
String name = elem->children.front()->getColumnName();
const auto & order_by_elem = elem->as<ASTOrderByElement &>();
std::shared_ptr<Collator> collator;
if (order_by_elem.collation)
collator = std::make_shared<Collator>(order_by_elem.collation->as<ASTLiteral &>().value.get<String>());
if (order_by_elem.with_fill)
{
FillColumnDescription fill_desc = getWithFillDescription(order_by_elem, context);
order_descr.emplace_back(name, order_by_elem.direction, order_by_elem.nulls_direction, collator, true, fill_desc);
}
else
order_descr.emplace_back(name, order_by_elem.direction, order_by_elem.nulls_direction, collator);
}
return order_descr;
}
static SortDescription getSortDescriptionFromGroupBy(const ASTSelectQuery & query)
{
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, ContextPtr context, const std::string & expr)
{
const auto & [field, type] = evaluateConstantExpression(node, context);
if (!isNativeNumber(type))
throw Exception(
"Illegal type " + type->getName() + " of " + expr + " expression, must be numeric type", ErrorCodes::INVALID_LIMIT_EXPRESSION);
Field converted = convertFieldToType(field, DataTypeUInt64());
if (converted.isNull())
throw Exception(
"The value " + applyVisitor(FieldVisitorToString(), field) + " of " + expr + " expression is not representable as UInt64",
ErrorCodes::INVALID_LIMIT_EXPRESSION);
return converted.safeGet<UInt64>();
}
static std::pair<UInt64, UInt64> getLimitLengthAndOffset(const ASTSelectQuery & query, 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};
}
static UInt64 getLimitForSorting(const ASTSelectQuery & query, 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<UInt64>::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<ASTSelectWithUnionQuery>())
{
/** 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<bool(ASTPtr)> traverse_recursively = [&](ASTPtr child_ast) -> bool
{
if (const auto * select_child = child_ast->as <ASTSelectQuery>())
{
if (hasWithTotalsInAnySubqueryInFromClause(select_child->as<ASTSelectQuery &>()))
return true;
}
else if (const auto * union_child = child_ast->as<ASTSelectWithUnionQuery>())
{
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<ASTSelectIntersectExceptQuery>())
{
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<Pipe> 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;
auto & subqueries_for_sets = query_analyzer->getSubqueriesForSets();
bool intermediate_stage = false;
bool to_aggregation_stage = false;
bool from_aggregation_stage = false;
/// Do I need to aggregate in a separate row rows that have 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;
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<ReadNothingStep>(source_header);
query_plan.addStep(std::move(read_nothing));
if (expressions.filter_info)
{
auto row_level_security_step = std::make_unique<FilterStep>(
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<FilterStep>(
query_plan.getCurrentDataStream(),
expressions.prewhere_info->row_level_filter,
expressions.prewhere_info->row_level_column_name,
false);
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<FilterStep>(
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<ReadFromPreparedSource>(std::move(*prepared_pipe), context);
query_plan.addStep(std::move(prepared_source_step));
}
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 (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,
query_info.input_order_info ? query_info.input_order_info
: (query_info.projection ? query_info.projection->input_order_info : nullptr));
if (expressions.has_order_by && query.limitLength())
executeDistinct(query_plan, false, expressions.selected_columns, true);
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("Query with intermediate stage cannot have any other stages", ErrorCodes::LOGICAL_ERROR);
preliminary_sort();
if (expressions.need_aggregate)
executeMergeAggregated(query_plan, aggregate_overflow_row, aggregate_final);
}
if (from_aggregation_stage)
{
if (intermediate_stage || expressions.first_stage || expressions.second_stage)
throw Exception("Query with after aggregation stage cannot have any other stages", ErrorCodes::LOGICAL_ERROR);
}
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<FilterStep>(
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.before_array_join)
{
QueryPlanStepPtr before_array_join_step
= std::make_unique<ExpressionStep>(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<ArrayJoinStep>(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<ExpressionStep>(
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<ExpressionStep>(
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<FilledJoinStep>(
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");
QueryPlanStepPtr join_step = std::make_unique<JoinStep>(
query_plan.getCurrentDataStream(),
joined_plan->getCurrentDataStream(),
expressions.join,
settings.max_block_size);
join_step->setStepDescription("JOIN");
std::vector<QueryPlanPtr> plans;
plans.emplace_back(std::make_unique<QueryPlan>(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);
/// We need to reset input order info, so that executeOrder can't use it
query_info.input_order_info.reset();
if (query_info.projection)
query_info.projection->input_order_info.reset();
}
// 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 there is no global subqueries, we can run subqueries only when receive them on server.
if (!query_analyzer->hasGlobalSubqueries() && !subqueries_for_sets.empty())
executeSubqueriesInSetsAndJoins(query_plan, subqueries_for_sets);
}
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);
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) && expressions.hasHaving())
{
if (query.group_by_with_totals)
throw Exception(
"WITH TOTALS and WITH ROLLUP or CUBE are not supported together in presence of HAVING",
ErrorCodes::NOT_IMPLEMENTED);
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)
throw Exception("WITH TOTALS, ROLLUP or CUBE are not supported without aggregation", ErrorCodes::NOT_IMPLEMENTED);
// 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(
"Window functions does not support processing from WithMergeableStateAfterAggregation",
ErrorCodes::NOT_IMPLEMENTED);
}
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,
query_info.input_order_info ? query_info.input_order_info
: (query_info.projection ? query_info.projection->input_order_info : nullptr));
}
/** 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);
}
}
if (!subqueries_for_sets.empty() && (expressions.hasHaving() || query_analyzer->hasGlobalSubqueries()))
executeSubqueriesInSetsAndJoins(query_plan, subqueries_for_sets);
}
static StreamLocalLimits getLimitsForStorage(const Settings & settings, const SelectQueryOptions & options)
{
StreamLocalLimits limits;
limits.mode = LimitsMode::LIMITS_TOTAL;
limits.size_limits = SizeLimits(settings.max_rows_to_read, settings.max_bytes_to_read, settings.read_overflow_mode);
limits.speed_limits.max_execution_time = settings.max_execution_time;
limits.timeout_overflow_mode = settings.timeout_overflow_mode;
/** Quota and minimal speed restrictions are checked on the initiating server of the request, and not on remote servers,
* because the initiating server has a summary of the execution of the request on all servers.
*
* But limits on data size to read and maximum execution time are reasonable to check both on initiator and
* additionally on each remote server, because these limits are checked per block of data processed,
* and remote servers may process way more blocks of data than are received by initiator.
*
* The limits to throttle maximum execution speed is also checked on all servers.
*/
if (options.to_stage == QueryProcessingStage::Complete)
{
limits.speed_limits.min_execution_rps = settings.min_execution_speed;
limits.speed_limits.min_execution_bps = settings.min_execution_speed_bytes;
}
limits.speed_limits.max_execution_rps = settings.max_execution_speed;
limits.speed_limits.max_execution_bps = settings.max_execution_speed_bytes;
limits.speed_limits.timeout_before_checking_execution_speed = settings.timeout_before_checking_execution_speed;
return limits;
}
static void executeMergeAggregatedImpl(
QueryPlan & query_plan,
bool overflow_row,
bool final,
bool is_remote_storage,
const Settings & settings,
const NamesAndTypesList & aggregation_keys,
const AggregateDescriptions & aggregates)
{
const auto & header_before_merge = query_plan.getCurrentDataStream().header;
ColumnNumbers keys;
for (const auto & key : aggregation_keys)
keys.push_back(header_before_merge.getPositionByName(key.name));
/** 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(header_before_merge, keys, aggregates, overflow_row, settings.max_threads);
auto transform_params = std::make_shared<AggregatingTransformParams>(params, final);
auto merging_aggregated = std::make_unique<MergingAggregatedStep>(
query_plan.getCurrentDataStream(),
std::move(transform_params),
settings.distributed_aggregation_memory_efficient && is_remote_storage,
settings.max_threads,
settings.aggregation_memory_efficient_merge_threads);
query_plan.addStep(std::move(merging_aggregated));
}
void InterpreterSelectQuery::addEmptySourceToQueryPlan(
QueryPlan & query_plan, const Block & source_header, const SelectQueryInfo & query_info, ContextPtr context_)
{
Pipe pipe(std::make_shared<NullSource>(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.alias_actions)
{
pipe.addSimpleTransform([&](const Block & header)
{
return std::make_shared<ExpressionTransform>(header,
std::make_shared<ExpressionActions>(prewhere_info.alias_actions));
});
}
if (prewhere_info.row_level_filter)
{
pipe.addSimpleTransform([&](const Block & header)
{
return std::make_shared<FilterTransform>(header,
std::make_shared<ExpressionActions>(prewhere_info.row_level_filter),
prewhere_info.row_level_column_name, true);
});
}
pipe.addSimpleTransform([&](const Block & header)
{
return std::make_shared<FilterTransform>(
header, std::make_shared<ExpressionActions>(prewhere_info.prewhere_actions),
prewhere_info.prewhere_column_name, prewhere_info.remove_prewhere_column);
});
}
auto read_from_pipe = std::make_unique<ReadFromPreparedSource>(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<FilterStep>(
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<ExpressionStep>(query_plan.getCurrentDataStream(), query_info.projection->before_aggregation);
expression_before_aggregation->setStepDescription("Before GROUP BY");
query_plan.addStep(std::move(expression_before_aggregation));
}
executeMergeAggregatedImpl(
query_plan,
query_info.projection->aggregate_overflow_row,
query_info.projection->aggregate_final,
false,
context_->getSettingsRef(),
query_info.projection->aggregation_keys,
query_info.projection->aggregate_descriptions);
}
}
}
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<PrewhereInfo>(
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;
}
}
/// 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; /// Set of all (including ALIAS) required columns for PREWHERE
NameSet required_aliases_from_prewhere; /// Set of ALIAS required columns for PREWHERE
if (prewhere_info)
{
/// Get some columns directly from PREWHERE expression actions
auto prewhere_required_columns = prewhere_info->prewhere_actions->getRequiredColumns().getNames();
required_columns_from_prewhere.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();
required_columns_from_prewhere.insert(row_level_required_columns.begin(), row_level_required_columns.end());
}
}
/// Expression, that contains all raw required columns
ASTPtr required_columns_all_expr = std::make_shared<ASTExpressionList>();
/// Expression, that contains raw required columns for PREWHERE
ASTPtr required_columns_from_prewhere_expr = std::make_shared<ASTExpressionList>();
/// 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<ASTIdentifier>(column);
if (required_columns_from_prewhere.count(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.count(column.name))
continue;
required_columns_all_expr->children.emplace_back(std::make_shared<ASTIdentifier>(column.name));
required_columns_after_prewhere.emplace_back(column.name, column.type);
}
required_columns_after_prewhere_set
= collections::map<NameSet>(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);
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.count(name) != 0; });
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);
auto analyzed_result
= TreeRewriter(context).analyze(required_columns_from_prewhere_expr, metadata_snapshot->getColumns().getAllPhysical());
prewhere_info->alias_actions
= ExpressionAnalyzer(required_columns_from_prewhere_expr, analyzed_result, context).getActionsDAG(true, false);
/// Add (physical?) columns required by alias actions.
auto required_columns_from_alias = prewhere_info->alias_actions->getRequiredColumns();
Block prewhere_actions_result = prewhere_info->prewhere_actions->getResultColumns();
for (auto & column : required_columns_from_alias)
if (!prewhere_actions_result.has(column.name))
if (required_columns.end() == std::find(required_columns.begin(), required_columns.end(), column.name))
required_columns.push_back(column.name);
/// Add physical columns required by prewhere actions.
for (const auto & column : required_columns_from_prewhere)
if (required_aliases_from_prewhere.count(column) == 0)
if (required_columns.end() == std::find(required_columns.begin(), required_columns.end(), column))
required_columns.push_back(column);
}
}
}
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
&& storage
&& storage->getName() != "MaterializedMySQL"
&& !row_policy_filter
&& processing_stage == QueryProcessingStage::FetchColumns
&& query_analyzer->hasAggregation()
&& (query_analyzer->aggregates().size() == 1)
&& typeid_cast<const AggregateFunctionCount *>(query_analyzer->aggregates()[0].function.get());
if (optimize_trivial_count)
{
const auto & desc = query_analyzer->aggregates()[0];
const auto & func = desc.function;
std::optional<UInt64> num_rows{};
if (!query.prewhere() && !query.where())
{
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.sets = query_analyzer->getPreparedSets();
num_rows = storage->totalRowsByPartitionPredicate(temp_query_info, context);
}
if (num_rows)
{
const AggregateFunctionCount & agg_count = static_cast<const AggregateFunctionCount &>(*func);
/// We will process it up to "WithMergeableState".
std::vector<char> 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<DataTypeAggregateFunction>(func, argument_types, desc.parameters), desc.column_name}};
auto source = std::make_shared<SourceFromSingleChunk>(block_with_count);
auto prepared_count = std::make_unique<ReadFromPreparedSource>(Pipe(std::move(source)), context);
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);
/** Optimization - if not specified DISTINCT, WHERE, GROUP, HAVING, ORDER, 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.groupBy()
&& !query.having()
&& !query.orderBy()
&& !query.limitBy()
&& query.limitLength()
&& !query_analyzer->hasAggregation()
&& !query_analyzer->hasWindow()
&& limit_length <= std::numeric_limits<UInt64>::max() - limit_offset
&& limit_length + limit_offset < max_block_size)
{
max_block_size = std::max(UInt64(1), limit_length + limit_offset);
max_threads_execute_query = max_streams = 1;
}
if (!max_block_size)
throw Exception("Setting 'max_block_size' cannot be zero", ErrorCodes::PARAMETER_OUT_OF_BOUND);
/// 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("Subquery expected", ErrorCodes::LOGICAL_ERROR);
interpreter_subquery = std::make_unique<InterpreterSelectWithUnionQuery>(
subquery, getSubqueryContext(context),
options.copy().subquery().noModify(), required_columns);
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 *= settings.max_streams_to_max_threads_ratio;
auto & prewhere_info = analysis_result.prewhere_info;
if (prewhere_info)
query_info.prewhere_info = prewhere_info;
/// Create optimizer with prepared actions.
/// Maybe we will need to calc input_order_info later, e.g. while reading from StorageMerge.
if ((analysis_result.optimize_read_in_order || analysis_result.optimize_aggregation_in_order)
&& (!query_info.projection || query_info.projection->complete))
{
if (analysis_result.optimize_read_in_order)
{
if (query_info.projection)
{
query_info.projection->order_optimizer = std::make_shared<ReadInOrderOptimizer>(
// 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<ReadInOrderOptimizer>(
query,
analysis_result.order_by_elements_actions,
getSortDescription(query, context),
query_info.syntax_analyzer_result);
}
}
else
{
if (query_info.projection)
{
query_info.projection->order_optimizer = std::make_shared<ReadInOrderOptimizer>(
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<ReadInOrderOptimizer>(
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);
}
StreamLocalLimits limits;
SizeLimits leaf_limits;
std::shared_ptr<const EnabledQuota> quota;
/// Set the limits and quota for reading data, the speed and time of the query.
if (!options.ignore_limits)
{
limits = getLimitsForStorage(settings, options);
leaf_limits = SizeLimits(settings.max_rows_to_read_leaf, settings.max_bytes_to_read_leaf, settings.read_overflow_mode_leaf);
}
if (!options.ignore_quota && (options.to_stage == QueryProcessingStage::Complete))
quota = context->getQuota();
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);
}
/// Extend lifetime of context, table lock, storage. Set limits and quota.
auto adding_limits_and_quota = std::make_unique<SettingQuotaAndLimitsStep>(
query_plan.getCurrentDataStream(), storage, std::move(table_lock), limits, leaf_limits, std::move(quota), context);
adding_limits_and_quota->setStepDescription("Set limits and quota after reading from storage");
query_plan.addStep(std::move(adding_limits_and_quota));
}
else
throw Exception("Logical error in InterpreterSelectQuery: nowhere to read", ErrorCodes::LOGICAL_ERROR);
/// 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<ExpressionStep>(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<FilterStep>(
query_plan.getCurrentDataStream(), expression, getSelectQuery().where()->getColumnName(), remove_filter);
where_step->setStepDescription("WHERE");
query_plan.addStep(std::move(where_step));
}
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<ExpressionStep>(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;
const auto & header_before_aggregation = query_plan.getCurrentDataStream().header;
ColumnNumbers keys;
for (const auto & key : query_analyzer->aggregationKeys())
keys.push_back(header_before_aggregation.getPositionByName(key.name));
AggregateDescriptions aggregates = query_analyzer->aggregates();
for (auto & descr : aggregates)
if (descr.arguments.empty())
for (const auto & name : descr.argument_names)
descr.arguments.push_back(header_before_aggregation.getPositionByName(name));
const Settings & settings = context->getSettingsRef();
Aggregator::Params params(
header_before_aggregation,
keys,
aggregates,
overflow_row,
settings.max_rows_to_group_by,
settings.group_by_overflow_mode,
settings.group_by_two_level_threshold,
settings.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->getTemporaryVolume(),
settings.max_threads,
settings.min_free_disk_space_for_temporary_data,
settings.compile_aggregate_expressions,
settings.min_count_to_compile_aggregate_expression);
SortDescription group_by_sort_description;
if (group_by_info && settings.optimize_aggregation_in_order)
group_by_sort_description = getSortDescriptionFromGroupBy(getSelectQuery());
else
group_by_info = nullptr;
auto merge_threads = max_streams;
auto temporary_data_merge_threads = settings.aggregation_memory_efficient_merge_threads
? static_cast<size_t>(settings.aggregation_memory_efficient_merge_threads)
: static_cast<size_t>(settings.max_threads);
bool storage_has_evenly_distributed_read = storage && storage->hasEvenlyDistributedRead();
auto aggregating_step = std::make_unique<AggregatingStep>(
query_plan.getCurrentDataStream(),
params,
final,
settings.max_block_size,
settings.aggregation_in_order_max_block_bytes,
merge_threads,
temporary_data_merge_threads,
storage_has_evenly_distributed_read,
std::move(group_by_info),
std::move(group_by_sort_description));
query_plan.addStep(std::move(aggregating_step));
}
void InterpreterSelectQuery::executeMergeAggregated(QueryPlan & query_plan, bool overflow_row, bool final)
{
/// 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;
executeMergeAggregatedImpl(
query_plan,
overflow_row,
final,
storage && storage->isRemote(),
context->getSettingsRef(),
query_analyzer->aggregationKeys(),
query_analyzer->aggregates());
}
void InterpreterSelectQuery::executeHaving(QueryPlan & query_plan, const ActionsDAGPtr & expression, bool remove_filter)
{
auto having_step
= std::make_unique<FilterStep>(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<TotalsHavingStep>(
query_plan.getCurrentDataStream(),
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 auto & header_before_transform = query_plan.getCurrentDataStream().header;
ColumnNumbers keys;
for (const auto & key : query_analyzer->aggregationKeys())
keys.push_back(header_before_transform.getPositionByName(key.name));
const Settings & settings = context->getSettingsRef();
Aggregator::Params params(
header_before_transform,
keys,
query_analyzer->aggregates(),
false,
settings.max_rows_to_group_by,
settings.group_by_overflow_mode,
0,
0,
settings.max_bytes_before_external_group_by,
settings.empty_result_for_aggregation_by_empty_set,
context->getTemporaryVolume(),
settings.max_threads,
settings.min_free_disk_space_for_temporary_data,
settings.compile_aggregate_expressions,
settings.min_count_to_compile_aggregate_expression);
auto transform_params = std::make_shared<AggregatingTransformParams>(params, true);
QueryPlanStepPtr step;
if (modificator == Modificator::ROLLUP)
step = std::make_unique<RollupStep>(query_plan.getCurrentDataStream(), std::move(transform_params));
else
step = std::make_unique<CubeStep>(query_plan.getCurrentDataStream(), std::move(transform_params));
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<ExpressionStep>(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].column_number < right[i].column_number)
return true;
else if (left[i].column_number > right[i].column_number)
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<const WindowDescription *> windows_sorted;
for (const auto & [_, w] : query_analyzer->windowDescriptions())
windows_sorted.push_back(&w);
::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 & w = *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 (!w.full_sort_description.empty() && (i == 0 || !sortIsPrefix(w, *windows_sorted[i - 1])))
{
auto sorting_step = std::make_unique<SortingStep>(
query_plan.getCurrentDataStream(),
w.full_sort_description,
settings.max_block_size,
0 /* LIMIT */,
SizeLimits(settings.max_rows_to_sort, settings.max_bytes_to_sort, settings.sort_overflow_mode),
settings.max_bytes_before_remerge_sort,
settings.remerge_sort_lowered_memory_bytes_ratio,
settings.max_bytes_before_external_sort,
context->getTemporaryVolume(),
settings.min_free_disk_space_for_temporary_data);
sorting_step->setStepDescription("Sorting for window '" + w.window_name + "'");
query_plan.addStep(std::move(sorting_step));
}
auto window_step = std::make_unique<WindowStep>(query_plan.getCurrentDataStream(), w, w.window_functions);
window_step->setStepDescription("Window step for window '" + w.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<SortingStep>(
query_plan.getCurrentDataStream(),
input_sorting_info->order_key_prefix_descr,
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();
/// Merge the sorted blocks.
auto sorting_step = std::make_unique<SortingStep>(
query_plan.getCurrentDataStream(),
output_order_descr,
settings.max_block_size,
limit,
SizeLimits(settings.max_rows_to_sort, settings.max_bytes_to_sort, settings.sort_overflow_mode),
settings.max_bytes_before_remerge_sort,
settings.remerge_sort_lowered_memory_bytes_ratio,
settings.max_bytes_before_external_sort,
context->getTemporaryVolume(),
settings.min_free_disk_space_for_temporary_data);
sorting_step->setStepDescription("Sorting for ORDER BY");
query_plan.addStep(std::move(sorting_step));
}
void InterpreterSelectQuery::executeMergeSorted(QueryPlan & query_plan, const std::string & description)
{
auto & query = getSelectQuery();
SortDescription order_descr = getSortDescription(query, context);
UInt64 limit = getLimitForSorting(query, context);
executeMergeSorted(query_plan, order_descr, limit, description);
}
void InterpreterSelectQuery::executeMergeSorted(QueryPlan & query_plan, const SortDescription & sort_description, UInt64 limit, const std::string & description)
{
const Settings & settings = context->getSettingsRef();
auto merging_sorted
= std::make_unique<SortingStep>(query_plan.getCurrentDataStream(), sort_description, settings.max_block_size, 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<ExpressionStep>(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();
auto [limit_length, limit_offset] = getLimitLengthAndOffset(query, context);
UInt64 limit_for_distinct = 0;
/// If after this stage of DISTINCT ORDER BY is not executed,
/// then you can get no more than limit_length + limit_offset of different rows.
if ((!query.orderBy() || !before_order) && limit_length <= std::numeric_limits<UInt64>::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<DistinctStep>(query_plan.getCurrentDataStream(), limits, limit_for_distinct, columns, pre_distinct);
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<UInt64>::max() - limit_offset)
return;
limit_length += limit_offset;
limit_offset = 0;
}
auto limit = std::make_unique<LimitStep>(query_plan.getCurrentDataStream(), limit_length, limit_offset);
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<LimitByStep>(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;
auto filling_step = std::make_unique<FillingStep>(query_plan.getCurrentDataStream(), std::move(fill_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.
*/
bool always_read_till_end = false;
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("LIMIT WITH TIES without ORDER BY", ErrorCodes::LOGICAL_ERROR);
order_descr = getSortDescription(query, context);
}
auto limit = std::make_unique<LimitStep>(
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<OffsetStep>(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<ExtremesStep>(query_plan.getCurrentDataStream());
query_plan.addStep(std::move(extremes_step));
}
void InterpreterSelectQuery::executeSubqueriesInSetsAndJoins(QueryPlan & query_plan, SubqueriesForSets & subqueries_for_sets)
{
const auto & input_order_info = query_info.input_order_info
? query_info.input_order_info
: (query_info.projection ? query_info.projection->input_order_info : nullptr);
if (input_order_info)
executeMergeSorted(query_plan, input_order_info->order_key_prefix_descr, 0, "before creating sets for subqueries and joins");
const Settings & settings = context->getSettingsRef();
SizeLimits limits(settings.max_rows_to_transfer, settings.max_bytes_to_transfer, settings.transfer_overflow_mode);
addCreatingSetsStep(query_plan, std::move(subqueries_for_sets), limits, context);
}
void InterpreterSelectQuery::ignoreWithTotals()
{
getSelectQuery().group_by_with_totals = false;
}
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));
}
}
}
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