greenplumn CWindowPreprocessor 源码
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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