// ---------------------------------------------------------------------
// Utility Routine: pickOutputs
//
// From the given ColStatDescList, populate columnStats_ with column
// descriptors that are useful based on the characteristic outputs for
// the group.
//
// Always include in the output the current histograms of the input data,
// and, if the histogram is contained in the required output list, then
// this is a useful histogram and will also be output.
//
// ---------------------------------------------------------------------
void EstLogProp::pickOutputs( ColStatDescList & columnStats,
const EstLogPropSharedPtr& inputEstLogProp,
const ValueIdSet specifiedOutputs,
const ValueIdSet predSet)
{
const ColStatDescList & outerColStatsList = inputEstLogProp->getColStats();
ValueIdSet colsRequiringHistograms = specifiedOutputs;
// (i) see if the selection predicates contain any constant value or a
// constant expression
// (ii) check if there are any columns of this table being joined to some other
// columns, which do not appear as characteristics outputs. There should be
// histograms available for these columns, as these might be needed later.
// This problem was seen for temporary tables created as normal_tables by the
// triggers.
colsRequiringHistograms.addSet(predSet.getColumnsForHistogram());
colStats().setMCSkewedValueLists(columnStats.getMCSkewedValueLists()) ;
NABoolean colStatDescAdded = FALSE;
for (CollIndex i=0; i < columnStats.entries(); i++)
{
// we probably don't need 'em all, but this is the easiest way to
// grab all of the multi-column uec information we'll need later
colStats().insertIntoUecList (columnStats.getUecList()) ;
colStats().setScanRowCountWithoutHint(columnStats.getScanRowCountWithoutHint());
NABoolean found = FALSE;
// Note: The following inserts into a ColStatDescList should not
// have to be deep copies. From this point on, ColStatDescs that
// describe the output of the calling operator are read-only.
ColStatDescSharedPtr colStatDesc = columnStats[i];
// the value-id we're looking for
const ValueId columnId = colStatDesc->getVEGColumn() ;
for (CollIndex j=0 ; j < outerColStatsList.entries() ; j++)
{
if (columnId == outerColStatsList[j]->getVEGColumn() OR
(CmpCommon::context()->showQueryStats()))
{
colStats().insert(colStatDesc) ;
found = TRUE;
if(!colStatDescAdded)
colStatDescAdded = TRUE;
break ; // jump to next ColStatDesc
}
}
// OK, the valueid doesn't match directly -- but there are still a
// couple of things to check in order to verify whether or not we're
// interested in keeping the i'th ColStatDesc ...
ValueId throwaway ; // used by the second clause below
if ( NOT found AND
(columnId != NULL_VALUE_ID) AND
(colsRequiringHistograms.contains (columnId) OR
colsRequiringHistograms.referencesTheGivenValue (columnId, throwaway) OR
columnId.isInvolvedInJoinAndConst() OR
CmpCommon::context()->showQueryStats() )
)
{
colStats().insert(colStatDesc);
found = TRUE;
if(!colStatDescAdded)
colStatDescAdded = TRUE;
}
if (CURRSTMT_OPTDEFAULTS->incorporateSkewInCosting())
{
// if the column is referenced for histogram, but is
// not needed beyond this time , then we shall save its
// max freq, which might be used later in costing if this
// column is a part of the partitioning key
ColStatsSharedPtr stat = colStatDesc->getColStats();
if (!(stat->isVirtualColForHist() ) && NOT found &&
!(stat->isOrigFakeHist() ) )
{
const ValueId col = colStatDesc->getColumn();
ColAnalysis * colAnalysis = col.colAnalysis();
if (colAnalysis)
{
NAColumn * column = stat->getStatColumns()[0];
if (column->isReferencedForHistogram())
{
CostScalar maxFreq = columnStats.getMaxFreq(columnId);
colAnalysis->setMaxFreq(maxFreq);
colAnalysis->setFinalUec(stat->getTotalUec());
colAnalysis->setFinalRC(stat->getRowcount());
}
}
}
}
} // for columnStats.entries()
if(!colStatDescAdded && columnStats.entries() > 0)
colStats().insert(columnStats[0]) ;
} // pickOutputs
