greenplumn CXformLeftOuterApply2LeftOuterJoin 代码
文件路径：/src/backend/gporca/libgpopt/src/xforms/CXformLeftOuterApply2LeftOuterJoin.cpp
/---------------------------------------------------------------------------
/ Greenplum Database
/ Copyright (C) 2012 EMC Corp.
/
/ @filename:
/ CXformLeftOuterApply2LeftOuterJoin.cpp
/
/ @doc:
/ Implementation of transform
/---------------------------------------------------------------------------
#include "gpopt/xforms/CXformLeftOuterApply2LeftOuterJoin.h"
#include "gpos/base.h"
using namespace gpopt;
/---------------------------------------------------------------------------
/ @function:
/ CXformLeftOuterApply2LeftOuterJoin::Exfp
/
/ @doc:
/ Compute xform promise for a given expression handle;
/ outer references are not allowed
/
/---------------------------------------------------------------------------
CXform::EXformPromise
CXformLeftOuterApply2LeftOuterJoin::Exfp(CExpressionHandle &exprhdl) const
{
/ if there are outer refs that include columns from the immediate outer child, the
/ transformation is applicable
if (exprhdl.HasOuterRefs(1 /*child_index*/) &&
!CUtils::FInnerUsesExternalColsOnly(exprhdl))
{
return CXform::ExfpHigh;
}
return CXform::ExfpNone;
}
/---------------------------------------------------------------------------
/ @function:
/ CXformLeftOuterApply2LeftOuterJoin::Transform
/
/ @doc:
/ Actual transformation
/
/---------------------------------------------------------------------------
void
CXformLeftOuterApply2LeftOuterJoin::Transform(CXformContext *pxfctxt,
CXformResult *pxfres,
CExpression *pexpr) const
{
GPOS_ASSERT(nullptr != pxfctxt);
GPOS_ASSERT(FPromising(pxfctxt->Pmp(), this, pexpr));
GPOS_ASSERT(FCheckPattern(pexpr));
Decorrelate(pxfctxt, pxfres, pexpr);
}
/ EOF
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