//----------------------------------------------------------------------------
// if the aggregation is MAX(A) then we can create two types of columns:
// INS_MAX_A = MAX(CASE @OP WHEN -1 THEN null ELSE SYS_DELTA.A).
// DEL_MAX_A = MAX(CASE @OP WHEN 1 THEN null ELSE SYS_DELTA.A).
// the 1 & -1 values will be refered to as constOpValue.
ItemExpr *MavRelRootBuilder::buildExtraMinMaxExpr(const ItemExpr *pMinMaxExpr,
const NAString& colName,
extraColumnType columnType) const
{
// if the pMinMaxExpr is the MAX(A) then pAggregationSubject is A.
ItemExpr *pAggregationSubject = pMinMaxExpr->child(0);
ItemExpr *copyOfAggSubject = pAggregationSubject->copyTree(heap_);
ColReference *opCol = new(heap_)
ColReference(new(heap_) ColRefName(MavBuilder::getVirtualOpColumnName()));
ConstValue *pConstOpValue = new(heap_)
SystemLiteral( (columnType == AGG_FOR_DELETE) ? 1 : -1);
Case *pCase = new(heap_)
Case(NULL, new(heap_)
IfThenElse(new(heap_) BiRelat(ITM_EQUAL, opCol, pConstOpValue),
new(heap_) SystemLiteral(), // NULL
copyOfAggSubject));
Aggregate *pNewAggregate = new(heap_)
Aggregate(pMinMaxExpr->getOperatorType(), pCase);
ColRefName *extraColName =
createExtraAggName(colName, columnType);
ItemExpr *result = new(heap_) RenameCol(pNewAggregate, extraColName);
return result;
} // buildExtraMinMaxExpr
//----------------------------------------------------------------------------
// The select list here is: (<fixed-count-cols>, <sum-col-refs>)
// The count cols become:
// Case( If <count-col> IS NULL THEN 0 ELSE <count-col>)
// Since the count cols were transformed from COUNT to SUM(@OP), They will
// now evaluate to NULL instead of 0 when no data is returned, for MAVs
// without a GROUP BY clause. This is what is fixed here.
//----------------------------------------------------------------------------
RelRoot *MavRelRootBuilder::buildRootForNoGroupBy(RelExpr *topNode)
{
ItemExprList selectList(heap_);
for (CollIndex i=0; i<countCols_.entries(); i++)
{
const MVColumnInfo *currentMavColumn = countCols_[i];
const NAString& colName = currentMavColumn->getColName();
// Build a col reference to the SYS_DELTA column.
ItemExpr *sysDeltaColExpr = new(heap_)
ColReference(new(heap_) ColRefName(colName, deltaCorrName_));
ItemExpr *condExpr = new(heap_)
Case(NULL, new(heap_)
IfThenElse(new(heap_) UnLogic(ITM_IS_NULL, sysDeltaColExpr),
new(heap_) SystemLiteral(0),
sysDeltaColExpr->copyTree(heap_)));
ItemExpr *renamedColExpr = new(heap_)
RenameCol(condExpr, new(heap_) ColRefName(colName, deltaCorrName_));
selectList.insert(renamedColExpr);
}
// Add the SUM cols.
addColsToSelectList(sumCols_, selectList, deltaCorrName_);
// Add the extra Min/Max columns.
selectList.insert(extraMinMaxColRefs_);
// The select list is ready. Create the root over topNode.
RelRoot *newRoot = new(heap_)
RelRoot(topNode, REL_ROOT, selectList.convertToItemExpr());
newRoot->setDontOpenNewScope();
selectList.clear();
return newRoot;
} // MavRelRootBuilder::buildRootForNoGroupBy()
