greenplumn CXformLeftOuterApply2LeftOuterJoinNoCorrelations 源码
greenplumn CXformLeftOuterApply2LeftOuterJoinNoCorrelations 代码
文件路径：/src/backend/gporca/libgpopt/src/xforms/CXformLeftOuterApply2LeftOuterJoinNoCorrelations.cpp
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2012 EMC Corp.
//
// @filename:
// CXformLeftOuterApply2LeftOuterJoinNoCorrelations.cpp
//
// @doc:
// Implementation of transform
//---------------------------------------------------------------------------
#include "gpopt/xforms/CXformLeftOuterApply2LeftOuterJoinNoCorrelations.h"
#include "gpos/base.h"
#include "gpopt/base/CUtils.h"
using namespace gpopt;
//---------------------------------------------------------------------------
// @function:
// CXformLeftOuterApply2LeftOuterJoinNoCorrelations::Exfp
//
// @doc:
// Compute xform promise for a given expression handle;
// outer references are not allowed
//
//---------------------------------------------------------------------------
CXform::EXformPromise
CXformLeftOuterApply2LeftOuterJoinNoCorrelations::Exfp(
CExpressionHandle &exprhdl) const
{
// if there are no outer references, or if all outer refs do not reference outer
// child, the transformation is applicable
if (!exprhdl.HasOuterRefs(1 /*child_index*/) ||
CUtils::FInnerUsesExternalColsOnly(exprhdl))
{
return CXform::ExfpHigh;
}
return CXform::ExfpNone;
}
//---------------------------------------------------------------------------
// @function:
// CXformLeftOuterApply2LeftOuterJoinNoCorrelations::Transform
//
// @doc:
// Actual transformation
//
//---------------------------------------------------------------------------
void
CXformLeftOuterApply2LeftOuterJoinNoCorrelations::Transform(
CXformContext *pxfctxt, CXformResult *pxfres, CExpression *pexpr) const
{
GPOS_ASSERT(nullptr != pxfctxt);
GPOS_ASSERT(FPromising(pxfctxt->Pmp(), this, pexpr));
GPOS_ASSERT(FCheckPattern(pexpr));
CreateJoinAlternative(pxfctxt, pxfres, pexpr);
}
// EOF
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