greenplumn CXformSimplifyGbAgg 源码
greenplumn CXformSimplifyGbAgg 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/xforms/CXformSimplifyGbAgg.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2012 EMC Corp.
//
// @filename:
// CXformSimplifyGbAgg.h
//
// @doc:
// Simplify an aggregate by splitting grouping columns into a set of
// functional dependencies in preparation for pushing Gb below join
//---------------------------------------------------------------------------
#ifndef GPOPT_CXformSimplifyGbAgg_H
#define GPOPT_CXformSimplifyGbAgg_H
#include "gpos/base.h"
#include "gpopt/xforms/CXformExploration.h"
namespace gpopt
{
using namespace gpos;
//---------------------------------------------------------------------------
// @class:
// CXformSimplifyGbAgg
//
// @doc:
// Simplify an aggregate by splitting grouping columns into a set of
// functional dependencies
//
//---------------------------------------------------------------------------
class CXformSimplifyGbAgg : public CXformExploration
{
private:
// helper to check if GbAgg can be transformed to a Select
static BOOL FDropGbAgg(CMemoryPool *mp, CExpression *pexpr,
CXformResult *pxfres);
public:
CXformSimplifyGbAgg(const CXformSimplifyGbAgg &) = delete;
// ctor
explicit CXformSimplifyGbAgg(CMemoryPool *mp);
// dtor
~CXformSimplifyGbAgg() override = default;
// ident accessors
EXformId
Exfid() const override
{
return ExfSimplifyGbAgg;
}
// return a string for xform name
const CHAR *
SzId() const override
{
return "CXformSimplifyGbAgg";
}
// Compatibility function for simplifying aggregates
BOOL
FCompatible(CXform::EXformId exfid) override
{
return (CXform::ExfSimplifyGbAgg != exfid) &&
(CXform::ExfSplitDQA != exfid) &&
(CXform::ExfSplitGbAgg != exfid) &&
(CXform::ExfEagerAgg != exfid);
}
// compute xform promise for a given expression handle
EXformPromise Exfp(CExpressionHandle &exprhdl) const override;
// actual transform
void Transform(CXformContext *, CXformResult *,
CExpression *) const override;
}; // class CXformSimplifyGbAgg
} // namespace gpopt
#endif // !GPOPT_CXformSimplifyGbAgg_H
// EOF
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