greenplumn CXformExpandFullOuterJoin 源码
greenplumn CXformExpandFullOuterJoin 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/xforms/CXformExpandFullOuterJoin.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2013 EMC Corp.
//
// @filename:
// CXformExpandFullOuterJoin.h
//
// @doc:
// Transform logical FOJ to a UNION ALL between LOJ and LASJ
//---------------------------------------------------------------------------
#ifndef GPOPT_CXformExpandFullOuterJoin_H
#define GPOPT_CXformExpandFullOuterJoin_H
#include "gpos/base.h"
#include "gpopt/xforms/CXformExploration.h"
namespace gpopt
{
using namespace gpos;
//---------------------------------------------------------------------------
// @class:
// CXformExpandFullOuterJoin
//
// @doc:
// Transform logical FOJ with a rename on top to a UNION ALL between LOJ
// and LASJ
//
//---------------------------------------------------------------------------
class CXformExpandFullOuterJoin : public CXformExploration
{
private:
// construct a join expression of two CTEs using the given CTE ids
// and output columns
static CExpression *PexprLogicalJoinOverCTEs(
CMemoryPool *mp, EdxlJoinType edxljointype, ULONG ulLeftCTEId,
CColRefArray *pdrgpcrLeft, ULONG ulRightCTEId,
CColRefArray *pdrgpcrRight, CExpression *pexprScalar);
public:
CXformExpandFullOuterJoin(const CXformExpandFullOuterJoin &) = delete;
// ctor
explicit CXformExpandFullOuterJoin(CMemoryPool *mp);
// dtor
~CXformExpandFullOuterJoin() override = default;
// ident accessors
EXformId
Exfid() const override
{
return ExfExpandFullOuterJoin;
}
// return a string for xform name
const CHAR *
SzId() const override
{
return "CXformExpandFullOuterJoin";
}
// 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 CXformExpandFullOuterJoin
} // namespace gpopt
#endif // !GPOPT_CXformExpandFullOuterJoin_H
// EOF
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