예제 #1
0
void computeAndAddSelParamIfPossible(
             CacheWA& cwa, BindWA& bindWA, ExprValueId& child,
             BaseColumn *base, ConstValue *val)
{
    ColStatsSharedPtr cStatsPtr = (base->getTableDesc()->tableColStats()).
                             getColStatsPtrForColumn(base->getValueId());

    if (cStatsPtr == NULL )
        return;

    HistogramSharedPtr hist = cStatsPtr->getHistogram();

    if ( hist == NULL )
       return;

    CostScalar sel;
    NABoolean canComputeSelectivity = hist -> computeSelectivityForEquality(
            val, cStatsPtr->getRowcount(), cStatsPtr->getTotalUec(),
            sel);

    if ( canComputeSelectivity == TRUE ) {
      const NAType * newType = base->getNAColumn()->getType();

      // for char datatypes, assign the caseinsensitive attribute from
      // the const node.
      if (newType->getTypeQualifier() == NA_CHARACTER_TYPE)
	{
	  newType = 
	    base->getNAColumn()->getType()->newCopy(cwa.wHeap());
	  ((CharType*)newType)->setCaseinsensitive(((CharType*)val->getType())->isCaseinsensitive());
	}
      
      cwa.replaceWithNewOrOldSelParam(val, newType, Selectivity(sel), 
                                      child, bindWA);

    }
}
예제 #2
0
// ---------------------------------------------------------------------
// 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