greenplumn CXformPushDownLeftOuterJoin 源码
greenplumn CXformPushDownLeftOuterJoin 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/xforms/CXformPushDownLeftOuterJoin.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2013 EMC Corp.
//
// @filename:
// CXformPushDownLeftOuterJoin.h
//
// @doc:
// Push LOJ below NAry join
//---------------------------------------------------------------------------
#ifndef GPOPT_CXformPushDownLeftOuterJoin_H
#define GPOPT_CXformPushDownLeftOuterJoin_H
#include "gpos/base.h"
#include "gpopt/xforms/CXformExploration.h"
namespace gpopt
{
using namespace gpos;
//---------------------------------------------------------------------------
// @class:
// CXformPushDownLeftOuterJoin
//
// @doc:
// Transform LOJ whose outer child is an NAry-join to be a child
// of NAry-join
//
//---------------------------------------------------------------------------
class CXformPushDownLeftOuterJoin : public CXformExploration
{
private:
public:
CXformPushDownLeftOuterJoin(const CXformPushDownLeftOuterJoin &) = delete;
// ctor
explicit CXformPushDownLeftOuterJoin(CMemoryPool *mp);
// dtor
~CXformPushDownLeftOuterJoin() override = default;
// xform promise
CXform::EXformPromise Exfp(CExpressionHandle &exprhdl) const override;
// ident accessors
EXformId
Exfid() const override
{
return ExfPushDownLeftOuterJoin;
}
// return a string for xform name
const CHAR *
SzId() const override
{
return "CXformPushDownLeftOuterJoin";
}
// actual transform
void Transform(CXformContext *pxfctxt, CXformResult *pxfres,
CExpression *pexpr) const override;
}; // class CXformPushDownLeftOuterJoin
} // namespace gpopt
#endif // !GPOPT_CXformPushDownLeftOuterJoin_H
// EOF
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