//---------------------------------------------------------------------------
// @function:
// CCostContext::FNeedsNewStats
//
// @doc:
// Check if we need to derive new stats for this context,
// by default a cost context inherits stats from the owner group,
// the only current exception is when part of the plan below cost
// context is affected by partition elimination done by partition
// selection in some other part of the plan
//
//---------------------------------------------------------------------------
BOOL
CCostContext::FNeedsNewStats() const
{
COperator *pop = m_pgexpr->Pop();
if (pop->FScalar())
{
// return false if scalar operator
return false;
}
CEnfdPartitionPropagation *pepp = Poc()->Prpp()->Pepp();
if (GPOS_FTRACE(EopttraceDeriveStatsForDPE) &&
CUtils::FPhysicalScan(pop) &&
CPhysicalScan::PopConvert(pop)->FDynamicScan() &&
!pepp->PpfmDerived()->FEmpty())
{
// context is attached to a dynamic scan that went through
// partition elimination in another part of the plan
return true;
}
// we need to derive stats if any child has modified stats
BOOL fDeriveStats = false;
const ULONG ulArity = Pdrgpoc()->UlLength();
for (ULONG ul = 0; !fDeriveStats && ul < ulArity; ul++)
{
COptimizationContext *pocChild = (*Pdrgpoc())[ul];
CCostContext *pccChild = pocChild->PccBest();
GPOS_ASSERT(NULL != pccChild);
fDeriveStats = pccChild->FOwnsStats();
}
return fDeriveStats;
}
