// getHistoryAttributes
//
// Helper function that traverses the set of root sequence functions
// supplied by the compiler and constructs the set of all of the
// attributes that must be materialized in the history row.
//
void PhysSequence::getHistoryAttributes(const ValueIdSet &sequenceFunctions,
const ValueIdSet &outputFromChild,
ValueIdSet &historyAttributes,
NABoolean addConvNodes,
CollHeap *wHeap,
ValueIdMap *origAttributes) const
{
if(addConvNodes && !origAttributes) {
origAttributes = new (wHeap) ValueIdMap();
}
ValueIdSet children;
for(ValueId valId = sequenceFunctions.init();
sequenceFunctions.next(valId);
sequenceFunctions.advance(valId)) {
if(valId.getItemExpr()->isASequenceFunction()) {
ItemExpr *itmExpr = valId.getItemExpr();
switch(itmExpr->getOperatorType())
{
// The child needs to be in the history row.
//
case ITM_OFFSET:
case ITM_ROWS_SINCE:
case ITM_THIS:
case ITM_NOT_THIS:
// If the child needs to be in the history buffer, then
// add a Convert node to force the value to be moved to the
// history buffer.
if (addConvNodes)
{
itmExpr->child(0) =
addConvNode(itmExpr->child(0), origAttributes, wHeap);
}
historyAttributes += itmExpr->child(0)->getValueId();
break;
// The sequence function needs to be in the history row.
//
case ITM_RUNNING_SUM:
case ITM_RUNNING_COUNT:
case ITM_RUNNING_MIN:
case ITM_RUNNING_MAX:
case ITM_LAST_NOT_NULL:
historyAttributes += itmExpr->getValueId();
break;
/*
// after PhysSequence precode gen OLAP sum and count are already transform,ed into running
// this is used during optimization phase--
case ITM_OLAP_SUM:
case ITM_OLAP_COUNT:
case ITM_OLAP_RANK:
case ITM_OLAP_DRANK:
if (addConvNodes)
{
itmExpr->child(0) =
addConvNode(itmExpr->child(0), origAttributes, wHeap);
}
historyAttributes += itmExpr->child(0)->getValueId();
//historyAttributes += itmExpr->getValueId();
break;
*/
// The child and sequence function need to be in the history row.
//
case ITM_OLAP_MIN:
case ITM_OLAP_MAX:
case ITM_MOVING_MIN:
case ITM_MOVING_MAX:
// If the child needs to be in the history buffer, then
// add a Convert node to force the value to be moved to the
// history buffer.
if (addConvNodes)
{
itmExpr->child(0) =
addConvNode(itmExpr->child(0), origAttributes, wHeap);
}
historyAttributes += itmExpr->child(0)->getValueId();
historyAttributes += itmExpr->getValueId();
break;
case ITM_RUNNING_CHANGE:
if (itmExpr->child(0)->getOperatorType() == ITM_ITEM_LIST)
{
// child is a multi-valued expression
//
ExprValueId treePtr = itmExpr->child(0);
ItemExprTreeAsList changeValues(&treePtr,
ITM_ITEM_LIST,
RIGHT_LINEAR_TREE);
CollIndex nc = changeValues.entries();
ItemExpr *newChild = NULL;
if(addConvNodes) {
newChild = addConvNode(changeValues[nc-1], origAttributes, wHeap);
historyAttributes += newChild->getValueId();
} else {
historyAttributes += changeValues[nc-1]->getValueId();
}
// add each item in the list
//
for (CollIndex i = nc; i > 0; i--)
{
if(addConvNodes) {
ItemExpr *conv
= addConvNode(changeValues[i-1], origAttributes, wHeap);
newChild = new(wHeap) ItemList(conv, newChild);
newChild->synthTypeAndValueId(TRUE);
historyAttributes += conv->getValueId();
} else {
historyAttributes += changeValues[i-1]->getValueId();
}
}
if(addConvNodes) {
itmExpr->child(0) = newChild;
}
}
else
{
// If the child needs to be in the history buffer, then
// add a Convert node to force the value to be moved to the
// history buffer.
if (addConvNodes)
{
itmExpr->child(0) =
addConvNode(itmExpr->child(0), origAttributes, wHeap);
}
historyAttributes += itmExpr->child(0)->getValueId();
}
historyAttributes += itmExpr->getValueId();
break;
default:
CMPASSERT(0);
}
}
// Gather all the children, and if not empty, recurse down to the
// next level of the tree.
//
for(Lng32 i = 0; i < valId.getItemExpr()->getArity(); i++)
{
if (!outputFromChild.contains(valId.getItemExpr()->child(i)->getValueId()))
//!valId.getItemExpr()->child(i)->nodeIsPreCodeGenned())
{
children += valId.getItemExpr()->child(i)->getValueId();
}
}
}
if (NOT children.isEmpty())
{
getHistoryAttributes( children,
outputFromChild,
historyAttributes,
addConvNodes,
wHeap,
origAttributes);
}
} // PhysSequence::getHistoryAttributes
// ItmSeqRunningFunction::preCodeGen
//
// Transforms the running sequence functions into scalar expressions
// that use offset to reference the previous value of the function.
//
ItemExpr *ItmSeqRunningFunction::preCodeGen(Generator *generator)
{
if (nodeIsPreCodeGenned())
return this;
markAsPreCodeGenned();
// Get some local handles...
//
CollHeap *wHeap = generator->wHeap();
ItemExpr *itmChild = child(0)->castToItemExpr();
// Allocate a HostVar for referencing the result before it is computed.
//
ItemExpr *itmResult
= new(wHeap) HostVar("_sys_Result",
getValueId().getType().newCopy(wHeap),
TRUE);
// Create an item expression to reference the previous
// value of this running sequence function.
//
ItemExpr *offExpr = new(wHeap) ItmSeqOffset(itmResult, 1);
((ItmSeqOffset *)offExpr)->setIsOLAP(isOLAP());
// Add the sequence function specific computation.
//
ItemExpr *itmNewSeqFunc = 0;
switch(getOperatorType())
{
case ITM_RUNNING_COUNT:
{
// By this point ITM_RUNNING_COUNT is count(column). The count
// is one more than the previous count if the current column is
// not null, otherwise, it is the previous count.
//
// Create the increment value. For non-nullable values, this
// is always 1, essentially runningcount(*).
//
ItemExpr *incr;
if(itmChild->getValueId().getType().supportsSQLnullLogical()) {
incr = generator->getExpGenerator()->createExprTree
("CASE WHEN @A1 IS NULL THEN @A3 ELSE @A2 END",
0, 3,
itmChild,
new(wHeap) ConstValue(1),
new(wHeap) ConstValue(0));
} else {
incr = new(wHeap) ConstValue(1);
}
((ItmSeqOffset *)offExpr)->setNullRowIsZero(TRUE);
ItemExpr *src = offExpr;
// Do the increment.
//
itmNewSeqFunc = new(wHeap)
BiArith(ITM_PLUS, src, incr);
}
break;
case ITM_RUNNING_SUM:
{
// SUM(sum from previous row, child)
//
itmNewSeqFunc = new(wHeap) BiArithSum(ITM_PLUS, offExpr, itmChild);
}
break;
case ITM_RUNNING_MIN:
{
// MIN(min from previous rows, child)
//
itmNewSeqFunc
= new(wHeap) ItmScalarMinMax(ITM_SCALAR_MIN,
offExpr,
itmChild);
}
break;
case ITM_RUNNING_MAX:
{
// MAX(max from previous row, child)
//
itmNewSeqFunc
= new(wHeap) ItmScalarMinMax(ITM_SCALAR_MAX,
offExpr,
itmChild);
}
break;
case ITM_LAST_NOT_NULL:
{
// If the current value is null then use the previous value
// of last not null.
//
itmNewSeqFunc = generator->getExpGenerator()->createExprTree
("CASE WHEN @A2 IS NOT NULL THEN @A2 ELSE @A1 END",
0, 2, offExpr, itmChild);
}
break;
case ITM_RUNNING_CHANGE:
{
// The running change (or 'rows since changed') can have a
// composite child (a list of values)
// Convert the list of values to a list of offset of values.
//
ItemExpr *offChild = itmChild;
if (itmChild->getOperatorType() == ITM_ITEM_LIST)
{
// child is a multi-valued expression, transform into multiple
//
ExprValueId treePtr = itmChild;
ItemExprTreeAsList changeValues(&treePtr,
ITM_ITEM_LIST,
RIGHT_LINEAR_TREE);
offChild = new(wHeap) ItmSeqOffset( changeValues[0], 1);
((ItmSeqOffset *)offChild)->setIsOLAP(isOLAP());
// add Offset expressions for all the items of the list
//
CollIndex nc = changeValues.entries();
for (CollIndex i = 1; i < nc; i++)
{
ItemExpr *off = new(generator->wHeap()) ItmSeqOffset( changeValues[i], 1);
((ItmSeqOffset *)off)->setIsOLAP(isOLAP());
offChild = new(generator->wHeap()) ItemList(offChild, off);
}
} else {
offChild = new(wHeap) ItmSeqOffset( offChild, 1);
((ItmSeqOffset *)offChild)->setIsOLAP(isOLAP());
}
((ItmSeqOffset *)offExpr)->setNullRowIsZero(TRUE);
ItemExpr *prevValue = offExpr;
// Compare the value(s) to the previous value(s). Use special
// NULLs flags to treat NULLs as values. Two NULL values are
// considered equal here.
//
ItemExpr *pred = new (wHeap) BiRelat(ITM_EQUAL,
itmChild,
offChild,
TRUE); // Special NULLs
// running change =
// (value(s) == prev(value(s))) ? prev(running change)+1 : 1
//
// Compute base value.
//
itmNewSeqFunc = new (wHeap)
IfThenElse(pred, prevValue, new (wHeap) SystemLiteral(0));
itmNewSeqFunc = new (wHeap) Case(NULL, itmNewSeqFunc);
// Force the evaluation of the offset expression so that the
// result can be reused by subsequent references.
//
itmNewSeqFunc = new(wHeap) ItmBlockFunction(offChild, itmNewSeqFunc);
// Increment the base value.
//
itmNewSeqFunc = new (wHeap) BiArith(ITM_PLUS,
itmNewSeqFunc,
new(wHeap) SystemLiteral(1));
}
break;
}
// Get value Ids and types for all of the items. Must do this typing before
// replacing this value Id's item expression -- otherwise, the typing
// will give a result different than the type already computed for this
// sequence function.
//
GenAssert(itmNewSeqFunc, "ItmSeqRunningFunction::preCodeGen -- Unexpected Operator Type!");
itmNewSeqFunc->synthTypeAndValueId(TRUE);
// Replace the original value ID with the new expression.
//
getValueId().replaceItemExpr(itmNewSeqFunc);
// Map the reference to the result to the actual result in the map table.
//
Attributes *attr = generator->getMapInfo
(itmNewSeqFunc->getValueId())->getAttr();
MapInfo *mapInfo = generator->addMapInfo(itmResult->getValueId(), attr);
itmResult->markAsPreCodeGenned();
mapInfo->codeGenerated();
// Return the preCodeGen of the new expression.
//
return itmNewSeqFunc->preCodeGen(generator);
}
