コード例 #1
0
//---------------------------------------------------------------------------
//	@function:
//		CXformDynamicGet2DynamicTableScan::Transform
//
//	@doc:
//		Actual transformation
//
//---------------------------------------------------------------------------
void
CXformDynamicGet2DynamicTableScan::Transform
	(
	CXformContext *pxfctxt,
	CXformResult *pxfres,
	CExpression *pexpr
	)
	const
{
	GPOS_ASSERT(NULL != pxfctxt);
	GPOS_ASSERT(FPromising(pxfctxt->Pmp(), this, pexpr));
	GPOS_ASSERT(FCheckPattern(pexpr));

	CLogicalDynamicGet *popGet = CLogicalDynamicGet::PopConvert(pexpr->Pop());
	IMemoryPool *pmp = pxfctxt->Pmp();

	// create/extract components for alternative
	CName *pname = GPOS_NEW(pmp) CName(pmp, popGet->Name());
	
	CTableDescriptor *ptabdesc = popGet->Ptabdesc();
	ptabdesc->AddRef();
	
	DrgPcr *pdrgpcrOutput = popGet->PdrgpcrOutput();
	GPOS_ASSERT(NULL != pdrgpcrOutput);

	pdrgpcrOutput->AddRef();
	
	DrgDrgPcr *pdrgpdrgpcrPart = popGet->PdrgpdrgpcrPart();
	pdrgpdrgpcrPart->AddRef();
	
	popGet->Ppartcnstr()->AddRef();
	popGet->PpartcnstrRel()->AddRef();
	
	// create alternative expression
	CExpression *pexprAlt = 
		GPOS_NEW(pmp) CExpression
			(
			pmp,
			GPOS_NEW(pmp) CPhysicalDynamicTableScan
						(
						pmp,
						popGet->FPartial(),
						pname, 
						ptabdesc,
						popGet->UlOpId(),
						popGet->UlScanId(), 
						pdrgpcrOutput,
						pdrgpdrgpcrPart,
						popGet->UlSecondaryScanId(),
						popGet->Ppartcnstr(),
						popGet->PpartcnstrRel()
						)
			);
	// add alternative to transformation result
	pxfres->Add(pexprAlt);
}
コード例 #2
0
//---------------------------------------------------------------------------
//	@function:
//		CXformSelect2PartialDynamicIndexGet::Transform
//
//	@doc:
//		Actual transformation
//
//---------------------------------------------------------------------------
void
CXformSelect2PartialDynamicIndexGet::Transform
	(
	CXformContext *pxfctxt,
	CXformResult *pxfres,
	CExpression *pexpr
	)
	const
{
	GPOS_ASSERT(NULL != pxfctxt);
	GPOS_ASSERT(FPromising(pxfctxt->Pmp(), this, pexpr));
	GPOS_ASSERT(FCheckPattern(pexpr));

	IMemoryPool *pmp = pxfctxt->Pmp();

	// extract components
	CExpression *pexprRelational = (*pexpr)[0];
	CExpression *pexprScalar = (*pexpr)[1];

	// get the indexes on this relation
	CLogicalDynamicGet *popGet = CLogicalDynamicGet::PopConvert(pexprRelational->Pop());
	
	if (popGet->FPartial())
	{
		// already a partial dynamic get; do not try to split further
		return;
	}
	
	CTableDescriptor *ptabdesc = popGet->Ptabdesc();
	CMDAccessor *pmda = COptCtxt::PoctxtFromTLS()->Pmda();
	const IMDRelation *pmdrel = pmda->Pmdrel(ptabdesc->Pmdid());
	const ULONG ulIndices = pmdrel->UlIndices();

	if (0 == ulIndices)
	{
		// no indexes on the table
		return;
	}

	// array of expressions in the scalar expression
	DrgPexpr *pdrgpexpr = CPredicateUtils::PdrgpexprConjuncts(pmp, pexprScalar);
	GPOS_ASSERT(0 < pdrgpexpr->UlLength());

	// derive the scalar and relational properties to build set of required columns
	CColRefSet *pcrsOutput = CDrvdPropRelational::Pdprel(pexpr->PdpDerive())->PcrsOutput();
	CColRefSet *pcrsScalarExpr = CDrvdPropScalar::Pdpscalar(pexprScalar->PdpDerive())->PcrsUsed();

	CColRefSet *pcrsReqd = GPOS_NEW(pmp) CColRefSet(pmp);
	pcrsReqd->Include(pcrsOutput);
	pcrsReqd->Include(pcrsScalarExpr);

	CPartConstraint *ppartcnstr = popGet->Ppartcnstr();
	ppartcnstr->AddRef();

	// find a candidate set of partial index combinations
	DrgPdrgPpartdig *pdrgpdrgppartdig = CXformUtils::PdrgpdrgppartdigCandidates
										(
										pmp,
										pmda,
										pdrgpexpr,
										popGet->PdrgpdrgpcrPart(),
										pmdrel,
										ppartcnstr,
										popGet->PdrgpcrOutput(),
										pcrsReqd,
										pcrsScalarExpr,
										NULL // pcrsAcceptedOuterRefs
										);
	
	// construct alternative partial index scan plans
	const ULONG ulCandidates = pdrgpdrgppartdig->UlLength();
	for (ULONG ul = 0; ul < ulCandidates; ul++)
	{
		DrgPpartdig *pdrgppartdig = (*pdrgpdrgppartdig)[ul];
		CreatePartialIndexGetPlan(pmp, pexpr, pdrgppartdig, pmdrel, pxfres);
	}

	ppartcnstr->Release();
	pcrsReqd->Release();
	pdrgpexpr->Release();
	pdrgpdrgppartdig->Release();
}