//---------------------------------------------------------------------------
// @function:
// CLogical::PpcDeriveConstraintFromPredicates
//
// @doc:
// Derive constraint property when expression has relational children and
// scalar children (predicates)
//
//---------------------------------------------------------------------------
CPropConstraint *
CLogical::PpcDeriveConstraintFromPredicates
(
IMemoryPool *pmp,
CExpressionHandle &exprhdl
)
{
DrgPcrs *pdrgpcrs = GPOS_NEW(pmp) DrgPcrs(pmp);
DrgPcnstr *pdrgpcnstr = GPOS_NEW(pmp) DrgPcnstr(pmp);
// collect constraint properties from relational children
// and predicates from scalar children
const ULONG ulArity = exprhdl.UlArity();
for (ULONG ul = 0; ul < ulArity; ul++)
{
if (exprhdl.FScalarChild(ul))
{
CExpression *pexprScalar = exprhdl.PexprScalarChild(ul);
// make sure it is a predicate... boolop, cmp, nulltest
if (NULL == pexprScalar || !CUtils::FPredicate(pexprScalar))
{
continue;
}
DrgPcrs *pdrgpcrsChild = NULL;
CConstraint *pcnstr = CConstraint::PcnstrFromScalarExpr(pmp, pexprScalar, &pdrgpcrsChild);
if (NULL != pcnstr)
{
pdrgpcnstr->Append(pcnstr);
// merge with the equivalence classes we have so far
DrgPcrs *pdrgpcrsMerged = CUtils::PdrgpcrsMergeEquivClasses(pmp, pdrgpcrs, pdrgpcrsChild);
pdrgpcrs->Release();
pdrgpcrs = pdrgpcrsMerged;
}
CRefCount::SafeRelease(pdrgpcrsChild);
}
else
{
CDrvdPropRelational *pdprel = exprhdl.Pdprel(ul);
CPropConstraint *ppc = pdprel->Ppc();
// equivalence classes coming from child
DrgPcrs *pdrgpcrsChild = ppc->PdrgpcrsEquivClasses();
// merge with the equivalence classes we have so far
DrgPcrs *pdrgpcrsMerged = CUtils::PdrgpcrsMergeEquivClasses(pmp, pdrgpcrs, pdrgpcrsChild);
pdrgpcrs->Release();
pdrgpcrs = pdrgpcrsMerged;
// constraint coming from child
CConstraint *pcnstr = ppc->Pcnstr();
if (NULL != pcnstr)
{
pcnstr->AddRef();
pdrgpcnstr->Append(pcnstr);
}
}
}
CConstraint *pcnstrNew = CConstraint::PcnstrConjunction(pmp, pdrgpcnstr);
return GPOS_NEW(pmp) CPropConstraint(pmp, pdrgpcrs, pcnstrNew);
}
