greenplumn CXformRightOuterJoin2HashJoin 代码
文件路径：/src/backend/gporca/libgpopt/src/xforms/CXformRightOuterJoin2HashJoin.cpp
/---------------------------------------------------------------------------
/ Greenplum Database
/ Copyright (c) 2020 VMware, Inc.
/
/ @filename:
/ CXformRightOuterJoin2HashJoin.cpp
/
/ @doc:
/ Implementation of transform
/---------------------------------------------------------------------------
#include "gpopt/xforms/CXformRightOuterJoin2HashJoin.h"
#include "gpos/base.h"
#include "gpopt/operators/CLogicalRightOuterJoin.h"
#include "gpopt/operators/CPatternLeaf.h"
#include "gpopt/operators/CPhysicalRightOuterHashJoin.h"
#include "gpopt/operators/CPredicateUtils.h"
#include "gpopt/xforms/CXformUtils.h"
using namespace gpopt;
/---------------------------------------------------------------------------
/ @function:
/ CXformRightOuterJoin2HashJoin::CXformRightOuterJoin2HashJoin
/
/ @doc:
/ ctor
/
/---------------------------------------------------------------------------
CXformRightOuterJoin2HashJoin::CXformRightOuterJoin2HashJoin(CMemoryPool *mp)
: / pattern
CXformImplementation(GPOS_NEW(mp) CExpression(
mp, GPOS_NEW(mp) CLogicalRightOuterJoin(mp),
GPOS_NEW(mp)
CExpression(mp, GPOS_NEW(mp) CPatternLeaf(mp)), / left child
GPOS_NEW(mp)
CExpression(mp, GPOS_NEW(mp) CPatternLeaf(mp)), / right child
GPOS_NEW(mp)
CExpression(mp, GPOS_NEW(mp) CPatternTree(mp)) / predicate
))
{
}
/---------------------------------------------------------------------------
/ @function:
/ CXformRightOuterJoin2HashJoin::Exfp
/
/ @doc:
/ Compute xform promise for a given expression handle;
/
/---------------------------------------------------------------------------
CXform::EXformPromise
CXformRightOuterJoin2HashJoin::Exfp(CExpressionHandle &exprhdl) const
{
return CXformUtils::ExfpLogicalJoin2PhysicalJoin(exprhdl);
}
/---------------------------------------------------------------------------
/ @function:
/ CXformRightOuterJoin2HashJoin::Transform
/
/ @doc:
/ actual transformation
/
/---------------------------------------------------------------------------
void
CXformRightOuterJoin2HashJoin::Transform(CXformContext *pxfctxt,
CXformResult *pxfres,
CExpression *pexpr) const
{
GPOS_ASSERT(nullptr != pxfctxt);
GPOS_ASSERT(FPromising(pxfctxt->Pmp(), this, pexpr));
GPOS_ASSERT(FCheckPattern(pexpr));
const IStatistics *outerStats = (*pexpr)[0]->Pstats();
const IStatistics *innerStats = (*pexpr)[1]->Pstats();
if (nullptr == outerStats || nullptr == innerStats)
{
return;
}
/ If the inner row estimate is an arbitary factor larger than the outer, don't generate a ROJ alternative.
/ Although the ROJ may still be better due to partition selection, which isn't considered below,
/ we're more cautious so we don't increase optimization time too much and that we account for
/ poor cardinality estimation. This is admittedly conservative, but mis-estimating the hash side
/ of a ROJ can cause spilling.
CDouble outerRows = outerStats->Rows();
CDouble outerWidth = outerStats->Width();
CDouble innerRows = innerStats->Rows();
CDouble innerWidth = innerStats->Width();
CDouble confidenceFactor = 2 * (*pexpr)[1]->DeriveJoinDepth();
if (innerRows * innerWidth * confidenceFactor > outerRows * outerWidth)
{
return;
}
CXformUtils::ImplementHashJoin<CPhysicalRightOuterHashJoin>(pxfctxt, pxfres,
pexpr);
}
/ EOF
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