// ***************************************************************************
// ***************************************************************************
NABoolean MVCandidate::matchPredsFromEQSetToSubGraph(const QRJoinSubGraphPtr mvSubGraph,
const QRJoinSubGraphPtr querySubGraph,
const JoinGraphEqualitySetPtr mvEqSet,
const JoinGraphEqualitySetPtr queryEqSet,
const NAString& mvHalfPredID)
{
NABoolean extraHubColumnChecked = FALSE;
const HalfPredicateList& queryHalfPreds = queryEqSet->getHalfPredicates();
CollIndex maxEntries = queryHalfPreds.entries();
for (CollIndex i=0; i<maxEntries; i++)
{
const JoinGraphHalfPredicatePtr queryHalfPred = queryHalfPreds[i];
const JoinGraphTablePtr queryTable = queryHalfPred->getTable();
if (querySubGraph->contains(queryTable))
{
// We found a join pred that's connected to the subgraph - match it.
// Find the corresponding table in the MV join graph.
// ??? Don't assert if a match is not found, because maybe the join pred
// ??? does not exist in the MV.
const BaseTableDetailsPtr mvBaseTable = getMvTableForQueryID(queryTable->getID(), FALSE);
if (mvBaseTable == NULL)
{
// Do we ever get here???
assertLogAndThrow(CAT_MVCAND, LL_MVQR_FAIL,
FALSE, QRLogicException,
"MV hub table corresponding to query hub not found.");
}
else
{
// We have the MV hub table corresponding to the query hub table.
// Now find its halfPred.
const NAString& mvID = mvBaseTable->getID();
const JoinGraphTablePtr mvTable = mvSubGraph->getParentGraph()->getTableByID(mvID);
const JoinGraphHalfPredicatePtr mvHalfPred = mvEqSet->findHalfPredTo(mvTable);
if (mvHalfPred == NULL)
{
// This query pred has no corresponding mv pred.
// Handle rewrite instructions here (Not implemented yet).
//if (addJoinPredForExtraHubTable(mvHalfPredID, queryHalfPred) == FALSE)
return FALSE;
}
else
{
// Finally we have both the MV halfPred and its corresponding query halfPred.
// Match them.
if (mvHalfPred->match(queryHalfPred) == FALSE)
return FALSE;
}
// Continue matching with the next halfPred.
continue;
}
}
}
return TRUE;
} // MVCandidate::matchPredsFromEQSetToSubGraph()
QRJbbSubsetPtr MVCandidatesForJBBSubset::generateDescriptor(CollHeap* heap)
{
// No candidates - no work.
if (candidateList_.entries() == 0)
return NULL;
// Construct the new QRJbbSubset object.
QRJbbSubsetPtr resultDesc = new(heap) QRJbbSubset(ADD_MEMCHECK_ARGS(heap));
resultDesc->setGroupBy(hasGroupBy_);
if (hasGroupBy_)
{
// Add a reference to the query NodeID of the GroupBy node.
const NAString& groupbyID =
getJbbCandidates()->getQueryJbb()->getGroupBy()->getID();
resultDesc->setRef(groupbyID);
}
// For each table included in the subgraph
QRJoinSubGraphPtr subGraph = querySubGraphMap_->getSubGraph();
for(subGraph->reset(); subGraph->hasNext(); subGraph->advance())
{
JoinGraphTablePtr table = subGraph->getCurrent();
// Add it to the JBBSubset descriptor.
QRTablePtr tableDesc = new(heap) QRTable(heap);
tableDesc->setTableName(table->getName());
tableDesc->setRef(table->getID());
resultDesc->addTable(tableDesc);
}
// If candidates are disqualified during the loop itself,
// Don't remove them from the list.
isLoopingOnCandidates_ = TRUE;
// Now add the MVCandidates.
CollIndex maxEntries = candidateList_.entries();
for (CollIndex i=0; i<maxEntries; i++)
{
MVCandidatePtr candidate = candidateList_[i];
if (candidate == NULL)
{
// The candidate was disqualified.
continue;
}
QRCandidatePtr candidateXml;
try
{
candidateXml = candidate->generateDescriptor();
}
catch (...)
{
candidate->logMVWasDisqualified("an exception was thrown.");
candidate->disqualify(); // Propagate the Info element to the result descriptor.
candidateXml = NULL;
}
if (candidateXml == NULL)
{
// The candidate was disqualified when generating the descriptor.
continue;
}
resultDesc->addCandidate(candidateXml);
}
if (resultDesc->getCandidateList()->entries() == 0)
{
// None of the candidates survived the result descriptor generation.
deletePtr(resultDesc);
return NULL;
}
return resultDesc;
} // MVCandidatesForJBBSubset::generateDescriptor()
