greenplumn CXformSimplifyLeftOuterJoin 源码
greenplumn CXformSimplifyLeftOuterJoin 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/xforms/CXformSimplifyLeftOuterJoin.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2013 VMware, Inc. or its affiliates.
//
// @filename:
// CXformSimplifyLeftOuterJoin.h
//
// @doc:
// Simplify Left Outer Join with constant false predicate
//---------------------------------------------------------------------------
#ifndef GPOPT_CXformSimplifyLeftOuterJoin_H
#define GPOPT_CXformSimplifyLeftOuterJoin_H
#include "gpos/base.h"
#include "gpopt/xforms/CXformExploration.h"
namespace gpopt
{
using namespace gpos;
//---------------------------------------------------------------------------
// @class:
// CXformSimplifyLeftOuterJoin
//
// @doc:
// Simplify Left Outer Join with constant false predicate
//
//---------------------------------------------------------------------------
class CXformSimplifyLeftOuterJoin : public CXformExploration
{
private:
public:
CXformSimplifyLeftOuterJoin(const CXformSimplifyLeftOuterJoin &) = delete;
// ctor
explicit CXformSimplifyLeftOuterJoin(CMemoryPool *mp);
// dtor
~CXformSimplifyLeftOuterJoin() override = default;
// ident accessors
EXformId
Exfid() const override
{
return ExfSimplifyLeftOuterJoin;
}
// return a string for xform name
const CHAR *
SzId() const override
{
return "CXformSimplifyLeftOuterJoin";
}
// Compatibility function for simplifying aggregates
BOOL
FCompatible(CXform::EXformId exfid) override
{
return (CXform::ExfSimplifyLeftOuterJoin != 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 CXformSimplifyLeftOuterJoin
} // namespace gpopt
#endif // !GPOPT_CXformSimplifyLeftOuterJoin_H
// EOF
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