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57 lines
1.6 KiB
C++
57 lines
1.6 KiB
C++
#pragma once
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#include <Core/Block.h>
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#include <Interpreters/Context_fwd.h>
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#include <Interpreters/InDepthNodeVisitor.h>
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#include <Common/typeid_cast.h>
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namespace DB
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{
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class ASTSubquery;
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class ASTFunction;
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struct ASTTableExpression;
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/** Replace subqueries that return exactly one row
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* ("scalar" subqueries) to the corresponding constants.
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*
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* If the subquery returns more than one column, it is replaced by a tuple of constants.
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*
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* Features
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*
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* A replacement occurs during query analysis, and not during the main runtime, so
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* the query result can be used for the index in the table.
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*
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* Scalar subqueries are executed on the request-initializer server.
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* The request is sent to remote servers with already substituted constants.
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*/
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class ExecuteScalarSubqueriesMatcher
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{
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public:
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using Visitor = InDepthNodeVisitor<ExecuteScalarSubqueriesMatcher, true>;
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struct Data : public WithContext
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{
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size_t subquery_depth;
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Scalars & scalars;
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Scalars & local_scalars;
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bool only_analyze;
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bool is_create_parameterized_view;
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bool replace_only_to_literals;
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std::optional<size_t> max_literal_size;
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};
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static bool needChildVisit(ASTPtr & node, const ASTPtr &);
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static void visit(ASTPtr & ast, Data & data);
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private:
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static void visit(const ASTSubquery & subquery, ASTPtr & ast, Data & data);
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static void visit(const ASTFunction & func, ASTPtr & ast, Data & data);
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};
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using ExecuteScalarSubqueriesVisitor = ExecuteScalarSubqueriesMatcher::Visitor;
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bool worthConvertingScalarToLiteral(const Block & scalar, std::optional<size_t> max_literal_size);
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}
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