C++ CExpressionHandle::FScalarChild方法代码示例

//---------------------------------------------------------------------------
//	@function:
//		CPhysical::FChildrenHaveCompatibleDistributions
//
//	@doc:
//		Returns true iff the delivered distributions of the children are
//		compatible among themselves.
//
//---------------------------------------------------------------------------
BOOL
CPhysical::FCompatibleChildrenDistributions
	(
	const CExpressionHandle &exprhdl
	)
	const
{
	GPOS_ASSERT(exprhdl.Pop() == this);
	BOOL fSingletonOrUniversalChild = false;
	BOOL fNotSingletonOrUniversalDistributedChild = false;
	const ULONG arity = exprhdl.Arity();
	for (ULONG ul = 0; ul < arity; ul++)
	{
		if (!exprhdl.FScalarChild(ul))
		{
			CDrvdPropPlan *pdpplanChild = exprhdl.Pdpplan(ul);

			// an operator cannot have a singleton or universal distributed child
			// and one distributed on multiple nodes
			// this assumption is safe for all current operators, but it can be
			// too conservative: we could allow for instance the following cases
			// * LeftOuterJoin (universal, distributed)
			// * AntiSemiJoin  (universal, distributed)
			// These cases can be enabled if considered necessary by overriding
			// this function.
			if (CDistributionSpec::EdtUniversal == pdpplanChild->Pds()->Edt() ||
				pdpplanChild->Pds()->FSingletonOrStrictSingleton())
			{
				fSingletonOrUniversalChild = true;
			}
			else
			{
				fNotSingletonOrUniversalDistributedChild = true;
			}
			if (fSingletonOrUniversalChild && fNotSingletonOrUniversalDistributedChild)
			{

				return false;
			}
		}
	}

	return true;
}

//---------------------------------------------------------------------------
//	@function:
//		CLogical::MaxcardDef
//
//	@doc:
//		Default max card for join and apply operators
//
//---------------------------------------------------------------------------
CMaxCard
CLogical::MaxcardDef
	(
	CExpressionHandle &exprhdl
	)
{
	const ULONG ulArity = exprhdl.UlArity();

	CMaxCard maxcard = exprhdl.Pdprel(0)->Maxcard();
	for (ULONG ul = 1; ul < ulArity - 1; ul++)
	{
		if (!exprhdl.FScalarChild(ul))
		{
			maxcard *= exprhdl.Pdprel(ul)->Maxcard();
		}
	}

	return maxcard;
}

//---------------------------------------------------------------------------
//	@function:
//		CDrvdPropScalar::Derive
//
//	@doc:
//		Derive scalar props
//
//---------------------------------------------------------------------------
void
CDrvdPropScalar::Derive
	(
	IMemoryPool *pmp,
	CExpressionHandle &exprhdl,
	CDrvdPropCtxt * // pdpctxt
	)
{
	CScalar *popScalar = CScalar::PopConvert(exprhdl.Pop());
	
	// call derivation functions on the operator
	GPOS_ASSERT(NULL == m_pcrsDefined);
	m_pcrsDefined = popScalar->PcrsDefined(pmp, exprhdl);

	GPOS_ASSERT(NULL == m_pcrsSetReturningFunction);
	m_pcrsSetReturningFunction = popScalar->PcrsSetReturningFunction(pmp, exprhdl);
	
	GPOS_ASSERT(NULL == m_pcrsUsed);
	m_pcrsUsed = popScalar->PcrsUsed(pmp, exprhdl);

	// derive function properties
	m_pfp = popScalar->PfpDerive(pmp, exprhdl);

	// add defined and used columns of children
	const ULONG ulArity = exprhdl.UlArity();
	for (ULONG i = 0; i < ulArity; i++)
	{
		// only propagate properties from scalar children
		if (exprhdl.FScalarChild(i))
		{
			m_pcrsDefined->Union(exprhdl.Pdpscalar(i)->PcrsDefined());
			m_pcrsUsed->Union(exprhdl.Pdpscalar(i)->PcrsUsed());
			m_pcrsSetReturningFunction->Union(exprhdl.Pdpscalar(i)->PcrsSetReturningFunction());
		}
		else
		{
			GPOS_ASSERT(CUtils::FSubquery(popScalar));

			// parent operator is a subquery, add outer references
			// from its relational child as used columns
 			m_pcrsUsed->Union(exprhdl.Pdprel(0)->PcrsOuter());
		}
	}

	// derive existence of subqueries
	GPOS_ASSERT(!m_fHasSubquery);
	m_fHasSubquery = popScalar->FHasSubquery(exprhdl);
	
	if (m_fHasSubquery)
	{
		m_ppartinfo = popScalar->PpartinfoDerive(pmp, exprhdl);
	}
	else
	{
		m_ppartinfo = GPOS_NEW(pmp) CPartInfo(pmp);
	}

	m_fHasNonScalarFunction = popScalar->FHasNonScalarFunction(exprhdl);

	if (COperator::EopScalarProjectList == exprhdl.Pop()->Eopid())
	{
		m_ulDistinctAggs = CScalarProjectList::UlDistinctAggs(exprhdl);
		m_fHasMultipleDistinctAggs = CScalarProjectList::FHasMultipleDistinctAggs(exprhdl);
	}

	if (COperator::EopScalarProjectElement == exprhdl.Pop()->Eopid())
	{
		if (m_fHasNonScalarFunction)
		{
			CScalarProjectElement *pspeProject = (CScalarProjectElement *)(exprhdl.Pop());
			m_pcrsSetReturningFunction->Include(pspeProject->Pcr());
		}
	}
}