greenplumn CWindowPreprocessor 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/operators/CWindowPreprocessor.h
/---------------------------------------------------------------------------
/ Greenplum Database
/ Copyright (C) 2015 VMware, Inc. or its affiliates.
/
/ @filename:
/ CWindowPreprocessor.h
/
/ @doc:
/ Preprocessing routines of window functions
/---------------------------------------------------------------------------
#ifndef GPOPT_CWindowPreprocessor_H
#define GPOPT_CWindowPreprocessor_H
#include "gpos/base.h"
#include "gpopt/base/COrderSpec.h"
#include "gpopt/base/CWindowFrame.h"
#include "gpopt/operators/CExpression.h"
namespace gpopt
{
/---------------------------------------------------------------------------
/ @class:
/ CWindowPreprocessor
/
/ @doc:
/ Preprocessing routines of window functions
/
/---------------------------------------------------------------------------
class CWindowPreprocessor
{
private:
/ iterate over project elements and split them elements between Distinct Aggs
/ list, and Others list
static void SplitPrjList(CMemoryPool *mp, CExpression *pexprSeqPrj,
CExpressionArray **ppdrgpexprDistinctAggsPrjElems,
CExpressionArray **ppdrgpexprOtherPrjElems,
gpopt::COrderSpecArray **ppdrgposOther,
gpopt::CWindowFrameArray **ppdrgpwfOther);
/ split given SeqPrj expression into:
/ - A GbAgg expression containing distinct Aggs, and
/ - A SeqPrj expression containing all other window functions
static void SplitSeqPrj(CMemoryPool *mp, CExpression *pexprSeqPrj,
CExpression **ppexprGbAgg,
CExpression **ppexprOutputSeqPrj);
/ create a CTE with two consumers using the child expression of Sequence
/ Project
static void CreateCTE(CMemoryPool *mp, CExpression *pexprSeqPrj,
CExpression **ppexprFirstConsumer,
CExpression **ppexprSecondConsumer);
/ extract grouping columns from given expression
static CColRefArray *PdrgpcrGrpCols(CExpression *pexprJoinDQAs);
/ transform sequence project expression into an inner join expression
static CExpression *PexprSeqPrj2Join(CMemoryPool *mp,
CExpression *pexprSeqPrj);
public:
CWindowPreprocessor(const CWindowPreprocessor &) = delete;
/ main driver
static CExpression *PexprPreprocess(CMemoryPool *mp, CExpression *pexpr);
}; / class CWindowPreprocessor
} / namespace gpopt
#endif / !GPOPT_CWindowPreprocessor_H
/ EOF
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