greenplumn CXformLeftSemiJoin2CrossProduct 代码
文件路径：/src/backend/gporca/libgpopt/src/xforms/CXformLeftSemiJoin2CrossProduct.cpp
/---------------------------------------------------------------------------
/ Greenplum Database
/ Copyright (C) 2013 EMC Corp.
/
/ @filename:
/ CXformLeftSemiJoin2CrossProduct.cpp
/
/ @doc:
/ Implementation of transform
/---------------------------------------------------------------------------
#include "gpopt/xforms/CXformLeftSemiJoin2CrossProduct.h"
#include "gpos/base.h"
#include "gpopt/operators/CLogicalInnerJoin.h"
#include "gpopt/operators/CLogicalLeftSemiJoin.h"
#include "gpopt/operators/CLogicalLimit.h"
#include "gpopt/operators/CNormalizer.h"
#include "gpopt/operators/CPatternLeaf.h"
#include "gpopt/operators/CPatternTree.h"
#include "gpopt/xforms/CXformUtils.h"
using namespace gpopt;
/---------------------------------------------------------------------------
/ @function:
/ CXformLeftSemiJoin2CrossProduct::CXformLeftSemiJoin2CrossProduct
/
/ @doc:
/ ctor
/
/---------------------------------------------------------------------------
CXformLeftSemiJoin2CrossProduct::CXformLeftSemiJoin2CrossProduct(
CMemoryPool *mp)
: / pattern
CXformExploration(GPOS_NEW(mp) CExpression(
mp, GPOS_NEW(mp) CLogicalLeftSemiJoin(mp),
GPOS_NEW(mp) CExpression(
mp,
GPOS_NEW(mp) CPatternTree(
mp)), / left child is a tree since we may need to push predicates down
GPOS_NEW(mp)
CExpression(mp, GPOS_NEW(mp) CPatternLeaf(mp)), / right child
GPOS_NEW(mp) CExpression(
mp,
GPOS_NEW(mp) CPatternTree(
mp)) / predicate is a tree since we may need to do clean-up of scalar expression
))
{
}
/---------------------------------------------------------------------------
/ @function:
/ CXformLeftSemiJoin2CrossProduct::Exfp
/
/ @doc:
/ Compute xform promise for a given expression handle
/
/---------------------------------------------------------------------------
CXform::EXformPromise
CXformLeftSemiJoin2CrossProduct::Exfp(CExpressionHandle &exprhdl) const
{
return CXformUtils::ExfpSemiJoin2CrossProduct(exprhdl);
}
/---------------------------------------------------------------------------
/ @function:
/ CXformLeftSemiJoin2CrossProduct::Transform
/
/ @doc:
/ Semi join whose join predicate does not use columns from join's inner
/ child is equivalent to a Cross Product between outer child (after
/ pushing join predicate), and one tuple from inner child
/
/---------------------------------------------------------------------------
void
CXformLeftSemiJoin2CrossProduct::Transform(CXformContext *pxfctxt,
CXformResult *pxfres,
CExpression *pexpr) const
{
GPOS_ASSERT(nullptr != pxfctxt);
GPOS_ASSERT(FPromising(pxfctxt->Pmp(), this, pexpr));
GPOS_ASSERT(FCheckPattern(pexpr));
CMemoryPool *mp = pxfctxt->Pmp();
/ extract components
CExpression *pexprOuter = (*pexpr)[0];
CExpression *pexprInner = (*pexpr)[1];
CExpression *pexprScalar = (*pexpr)[2];
pexprOuter->AddRef();
pexprInner->AddRef();
pexprScalar->AddRef();
/ create a (limit 1) on top of inner child
CExpression *pexprLimitOffset = CUtils::PexprScalarConstInt8(mp, 0 /*val*/);
CExpression *pexprLimitCount = CUtils::PexprScalarConstInt8(mp, 1 /*val*/);
COrderSpec *pos = GPOS_NEW(mp) COrderSpec(mp);
CLogicalLimit *popLimit = GPOS_NEW(mp)
CLogicalLimit(mp, pos, true /*fGlobal*/, true /*fHasCount*/,
false /*fNonRemovableLimit*/);
CExpression *pexprLimit = GPOS_NEW(mp) CExpression(
mp, popLimit, pexprInner, pexprLimitOffset, pexprLimitCount);
/ create cross product
CExpression *pexprJoin = CUtils::PexprLogicalJoin<CLogicalInnerJoin>(
mp, pexprOuter, pexprLimit, pexprScalar);
CExpression *pexprNormalized = CNormalizer::PexprNormalize(mp, pexprJoin);
pexprJoin->Release();
pxfres->Add(pexprNormalized);
}
/ EOF
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