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23 lines
584 B
C++
23 lines
584 B
C++
#pragma once
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#include <Parsers/IAST.h>
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#include <Interpreters/InDepthNodeVisitor.h>
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#include "Interpreters/TreeRewriter.h"
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namespace DB
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{
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class ASTFunction;
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/// Really simple rewrite 'select countDistinct(a) from t' to 'select count(1) from (select a from t groupBy a)'
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class RewriteCountDistinctFunctionMatcher
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{
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public:
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struct Data {};
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static void visit(ASTPtr & ast, Data &);
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static bool needChildVisit(const ASTPtr &, const ASTPtr &) { return true; }
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};
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using RewriteCountDistinctFunctionVisitor = InDepthNodeVisitor<RewriteCountDistinctFunctionMatcher, true>;
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}
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