greenplumn CXformSplitGbAgg 源码
greenplumn CXformSplitGbAgg 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/xforms/CXformSplitGbAgg.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2012 EMC Corp.
//
// @filename:
// CXformSplitGbAgg.h
//
// @doc:
// Split an aggregate into a pair of local and global aggregate
//---------------------------------------------------------------------------
#ifndef GPOPT_CXformSplitGbAgg_H
#define GPOPT_CXformSplitGbAgg_H
#include "gpos/base.h"
#include "gpopt/xforms/CXformExploration.h"
namespace gpopt
{
using namespace gpos;
//---------------------------------------------------------------------------
// @class:
// CXformSplitGbAgg
//
// @doc:
// Split an aggregate operator into pair of local and global aggregate
//
//---------------------------------------------------------------------------
class CXformSplitGbAgg : public CXformExploration
{
private:
protected:
// check if the transformation is applicable;
static BOOL FApplicable(CExpression *pexpr);
// generate a project lists for the local and global aggregates
// from the original aggregate
static void PopulateLocalGlobalProjectList(
CMemoryPool *mp, // memory pool
CExpression *
pexprProjListOrig, // project list of the original global aggregate
CExpression *
*ppexprProjListLocal, // project list of the new local aggregate
CExpression *
*ppexprProjListGlobal // project list of the new global aggregate
);
public:
CXformSplitGbAgg(const CXformSplitGbAgg &) = delete;
// ctor
explicit CXformSplitGbAgg(CMemoryPool *mp);
// ctor
explicit CXformSplitGbAgg(CExpression *pexprPattern);
// dtor
~CXformSplitGbAgg() override = default;
// ident accessors
EXformId
Exfid() const override
{
return ExfSplitGbAgg;
}
// return a string for xform name
const CHAR *
SzId() const override
{
return "CXformSplitGbAgg";
}
// Compatibility function for splitting aggregates
BOOL
FCompatible(CXform::EXformId exfid) override
{
return ((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 *pxfctxt, CXformResult *pxfres,
CExpression *pexpr) const override;
}; // class CXformSplitGbAgg
} // namespace gpopt
#endif // !GPOPT_CXformSplitGbAgg_H
// EOF
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