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120 lines
4.9 KiB
C++
120 lines
4.9 KiB
C++
#include <Interpreters/PredicateRewriteVisitor.h>
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#include <Parsers/ASTFunction.h>
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#include <Parsers/ASTAsterisk.h>
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#include <Parsers/ASTSubquery.h>
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#include <Parsers/ASTIdentifier.h>
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#include <Parsers/ASTColumnsMatcher.h>
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#include <Parsers/ASTQualifiedAsterisk.h>
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#include <Interpreters/IdentifierSemantic.h>
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#include <Interpreters/getTableExpressions.h>
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#include <Interpreters/InterpreterSelectQuery.h>
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#include <Interpreters/ExtractExpressionInfoVisitor.h>
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#include <AggregateFunctions/AggregateFunctionFactory.h>
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namespace DB
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{
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PredicateRewriteVisitorData::PredicateRewriteVisitorData(
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const Context & context_, const ASTs & predicates_, const Names & column_names_, bool optimize_final_)
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: context(context_), predicates(predicates_), column_names(column_names_), optimize_final(optimize_final_)
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{
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}
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void PredicateRewriteVisitorData::visit(ASTSelectWithUnionQuery & union_select_query, ASTPtr &)
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{
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auto & internal_select_list = union_select_query.list_of_selects->children;
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if (internal_select_list.size() > 0)
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visitFirstInternalSelect(*internal_select_list[0]->as<ASTSelectQuery>(), internal_select_list[0]);
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for (size_t index = 1; index < internal_select_list.size(); ++index)
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visitOtherInternalSelect(*internal_select_list[index]->as<ASTSelectQuery>(), internal_select_list[index]);
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}
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void PredicateRewriteVisitorData::visitFirstInternalSelect(ASTSelectQuery & select_query, ASTPtr &)
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{
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is_rewrite |= rewriteSubquery(select_query, column_names, column_names);
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}
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void PredicateRewriteVisitorData::visitOtherInternalSelect(ASTSelectQuery & select_query, ASTPtr &)
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{
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/// For non first select, its alias has no more significance, so we can set a temporary alias for them
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ASTPtr temp_internal_select = select_query.clone();
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ASTSelectQuery * temp_select_query = temp_internal_select->as<ASTSelectQuery>();
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size_t alias_index = 0;
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for (auto & ref_select : temp_select_query->refSelect()->children)
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{
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if (!ref_select->as<ASTAsterisk>() && !ref_select->as<ASTQualifiedAsterisk>() && !ref_select->as<ASTColumnsMatcher>() &&
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!ref_select->as<ASTIdentifier>())
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{
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if (const auto & alias = ref_select->tryGetAlias(); alias.empty())
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ref_select->setAlias("--predicate_optimizer_" + toString(alias_index++));
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}
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}
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const Names & internal_columns = InterpreterSelectQuery(
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temp_internal_select, context, SelectQueryOptions().analyze()).getSampleBlock().getNames();
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if (rewriteSubquery(*temp_select_query, column_names, internal_columns))
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{
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is_rewrite |= true;
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select_query.setExpression(ASTSelectQuery::Expression::SELECT, std::move(temp_select_query->refSelect()));
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select_query.setExpression(ASTSelectQuery::Expression::HAVING, std::move(temp_select_query->refHaving()));
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}
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}
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static void cleanAliasAndCollectIdentifiers(ASTPtr & predicate, std::vector<ASTIdentifier *> & identifiers)
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{
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/// Skip WHERE x in (SELECT ...)
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if (!predicate->as<ASTSubquery>())
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{
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for (auto & children : predicate->children)
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cleanAliasAndCollectIdentifiers(children, identifiers);
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}
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if (const auto alias = predicate->tryGetAlias(); !alias.empty())
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predicate->setAlias("");
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if (ASTIdentifier * identifier = predicate->as<ASTIdentifier>())
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identifiers.emplace_back(identifier);
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}
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bool PredicateRewriteVisitorData::rewriteSubquery(ASTSelectQuery & subquery, const Names & outer_columns, const Names & inner_columns)
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{
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if ((!optimize_final && subquery.final())
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|| subquery.with() || subquery.withFill()
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|| subquery.limitBy() || subquery.limitLength()
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|| hasStatefulFunction(subquery.select(), context))
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return false;
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for (const auto & predicate : predicates)
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{
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std::vector<ASTIdentifier *> identifiers;
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ASTPtr optimize_predicate = predicate->clone();
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cleanAliasAndCollectIdentifiers(optimize_predicate, identifiers);
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for (size_t index = 0; index < identifiers.size(); ++index)
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{
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const auto & column_name = identifiers[index]->shortName();
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const auto & outer_column_iterator = std::find(outer_columns.begin(), outer_columns.end(), column_name);
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/// For lambda functions, we can't always find them in the list of columns
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/// For example: SELECT * FROM system.one WHERE arrayMap(x -> x, [dummy]) = [0]
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if (outer_column_iterator != outer_columns.end())
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identifiers[index]->setShortName(inner_columns[outer_column_iterator - outer_columns.begin()]);
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}
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/// We only need to push all the predicates to subquery having
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/// The subquery optimizer will move the appropriate predicates from having to where
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subquery.setExpression(ASTSelectQuery::Expression::HAVING,
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subquery.having() ? makeASTFunction("and", optimize_predicate, subquery.having()) : optimize_predicate);
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}
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return true;
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}
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}
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