ItemExpr *ItmSeqOlapFunction::preCodeGen(Generator *generator)
{
if (getOperatorType() != ITM_OLAP_MIN && getOperatorType() != ITM_OLAP_MAX)
{
GenAssert(0, "ItmSeqOlapFunction::preCodeGen -- Should never get here!");
return 0;
}
if (nodeIsPreCodeGenned())
return this;
markAsPreCodeGenned();
// Get some local handles...
//
CollHeap *wHeap = generator->wHeap();
ItemExpr *itmChild = child(0)->castToItemExpr();
//ItemExpr *itmWindow = child(1)->castToItemExpr();
// What scalar operation needs to be done.
//
OperatorTypeEnum operation;
if(getOperatorType() == ITM_OLAP_MIN) operation = ITM_SCALAR_MIN;
else operation = ITM_SCALAR_MAX;
// Allocate a HostVar for local storage of the index.
//
ItemExpr *itmLocalCounter
= new(wHeap) HostVar("_sys_LocalCounter",
new(wHeap) SQLInt(wHeap, TRUE,FALSE),
TRUE);
// Expression to initailize the iterator.
//
ItemExpr *itmLocalCounterInitialize
= new(wHeap) Assign(itmLocalCounter,
new(wHeap) ConstValue(frameStart_),
FALSE);
// Expression to increment the iterator.
//
ItemExpr *itmLocalCounterIncrement
= new(wHeap) Assign(itmLocalCounter,
new(wHeap) BiArith(ITM_PLUS,
itmLocalCounter,
new (wHeap) ConstValue(1)),
FALSE);
// Allocate a HostVar for referencing the result before it is computed.
//
ItemExpr *itmResult
= new(wHeap) HostVar("_sys_Result",
getValueId().getType().newCopy(wHeap),
TRUE);
// Expression to initialize the result.
//
ItemExpr *itmResultInitialize
= new(wHeap) Assign(itmResult,
new(wHeap) ConstValue());
// Expression to compute the min/max.
//
ItemExpr * invCouter= new(wHeap) BiArith(ITM_MINUS,
new (wHeap) ConstValue(0),
itmLocalCounter);
ItemExpr * itmOffsetExpr = new(wHeap) ItmSeqOffset( itmChild, invCouter);
//ItemExpr * itmOffsetIsNotNull = new (wHeap) UnLogic(ITM_IS_NOT_NULL, itmOffsetExpr);
((ItmSeqOffset *)itmOffsetExpr)->setIsOLAP(isOLAP());
ItemExpr *itmResultUpdate
= new(wHeap) Assign(itmResult,
new(wHeap) ItmScalarMinMax(operation,
itmResult,
itmOffsetExpr));
// Construct code blocks for the initialization and body for the while-loop
//
ItemExpr *itmInit
= new(wHeap) ItmBlockFunction(itmLocalCounterInitialize,
itmResultInitialize);
ItemExpr *itmBody
= new(wHeap) ItmBlockFunction(itmResultUpdate,
itmLocalCounterIncrement);
// Construct the While loop (i < window)
//
ItemExpr *itmLoopCondition = new(wHeap) BiRelat
(ITM_LESS_EQ, itmLocalCounter, new(wHeap) ConstValue(frameEnd_));
if (isFrameEndUnboundedFollowing()) //(frameEnd_ == INT_MAX)// not needed in other cases -- can cause issues fo the preceding part
{
ItemExpr * itmOffset1 = new(wHeap) ItmSeqOffset( itmChild, invCouter,NULL,TRUE);
ItemExpr * itmOffset1IsNotNull = new (wHeap) UnLogic(ITM_IS_NOT_NULL, itmOffset1);
((ItmSeqOffset *)itmOffset1)->setIsOLAP(isOLAP());
itmLoopCondition = itmOffset1IsNotNull;
//new (wHeap) BiLogic( ITM_AND,
// itmLoopCondition,
// itmOffset1IsNotNull);
}
ItemExpr *itmWhile
= new(wHeap) ItmWhileFunction(itmBody,
itmLoopCondition);
// Construct the blocks to contain the initialization and looping.
// The result is the final value of the min/max.
//
ItemExpr *itmBlock = new(wHeap) ItmBlockFunction
(new(wHeap) ItmBlockFunction(itmInit, itmWhile),
itmResult);
// Replace the item for this value id with the new item expression.
//
getValueId().replaceItemExpr(itmBlock);
// Run the new expression through type and value Id synthesis.
//
itmBlock->synthTypeAndValueId(TRUE);
// Map the reference to the result to the actual result in the map table.
//
Attributes *attr = generator->getMapInfo(itmBlock->getValueId())->getAttr();
MapInfo *mapInfo = generator->addMapInfo(itmResult->getValueId(), attr);
itmResult->markAsPreCodeGenned();
mapInfo->codeGenerated();
// Return the preCodeGen of the new expression.
//
return itmBlock->preCodeGen(generator);
}
// ItmSeqMovingFunction::preCodeGen
//
// All of the moving sequence functions have been transformed away at this
// point except min and max. Transform these operations to a while-loop which
// iterates over the past rows testing the min/max condition for each row.
// Use the ItmScalarMin/Max functions for computing the min/max.
//
ItemExpr *ItmSeqMovingFunction::preCodeGen(Generator *generator)
{
if (nodeIsPreCodeGenned())
return this;
markAsPreCodeGenned();
// Get some local handles...
//
CollHeap *wHeap = generator->wHeap();
ItemExpr *itmChild = child(0)->castToItemExpr();
ItemExpr *itmWindow = child(1)->castToItemExpr();
// What scalar operation needs to be done.
//
OperatorTypeEnum operation;
if(getOperatorType() == ITM_MOVING_MIN) operation = ITM_SCALAR_MIN;
else operation = ITM_SCALAR_MAX;
// Allocate a HostVar for local storage of the index.
//
ItemExpr *itmLocalCounter
= new(wHeap) HostVar("_sys_LocalCounter",
new(wHeap) SQLInt(wHeap, TRUE,FALSE),
TRUE);
// Expression to initailize the iterator.
//
ItemExpr *itmLocalCounterInitialize
= new(wHeap) Assign(itmLocalCounter,
new(wHeap) ConstValue(0),
FALSE);
// Expression to increment the iterator.
//
ItemExpr *itmLocalCounterIncrement
= new(wHeap) Assign(itmLocalCounter,
new(wHeap) BiArith(ITM_PLUS,
itmLocalCounter,
new (wHeap) ConstValue(1)),
FALSE);
// Allocate a HostVar for referencing the result before it is computed.
//
ItemExpr *itmResult
= new(wHeap) HostVar("_sys_Result",
getValueId().getType().newCopy(wHeap),
TRUE);
// Expression to initialize the result.
//
ItemExpr *itmResultInitialize
= new(wHeap) Assign(itmResult,
new(wHeap) ConstValue());
// Expression to compute the min/max.
//
ItemExpr *itmOffsetExpr = new(wHeap) ItmSeqOffset( itmChild, itmLocalCounter);
((ItmSeqOffset *)itmOffsetExpr)->setIsOLAP(isOLAP());
ItemExpr *itmResultUpdate
= new(wHeap) Assign(itmResult,
new(wHeap) ItmScalarMinMax(operation,
itmResult,
itmOffsetExpr));
// Construct code blocks for the initialization and body for the while-loop
//
ItemExpr *itmInit
= new(wHeap) ItmBlockFunction(itmLocalCounterInitialize,
itmResultInitialize);
ItemExpr *itmBody
= new(wHeap) ItmBlockFunction(itmResultUpdate,
itmLocalCounterIncrement);
// Construct the While loop (i < window)
//
ItemExpr *itmLoopCondition = new(wHeap) BiRelat
(ITM_LESS, itmLocalCounter, itmWindow);
ItemExpr *itmWhile
= new(wHeap) ItmWhileFunction(itmBody,
itmLoopCondition);
// Construct the blocks to contain the initialization and looping.
// The result is the final value of the min/max.
//
ItemExpr *itmBlock = new(wHeap) ItmBlockFunction
(new(wHeap) ItmBlockFunction(itmInit, itmWhile),
itmResult);
// Replace the item for this value id with the new item expression.
//
getValueId().replaceItemExpr(itmBlock);
// Run the new expression through type and value Id synthesis.
//
itmBlock->synthTypeAndValueId(TRUE);
// Map the reference to the result to the actual result in the map table.
//
Attributes *attr = generator->getMapInfo(itmBlock->getValueId())->getAttr();
MapInfo *mapInfo = generator->addMapInfo(itmResult->getValueId(), attr);
itmResult->markAsPreCodeGenned();
mapInfo->codeGenerated();
// Return the preCodeGen of the new expression.
//
return itmBlock->preCodeGen(generator);
}
// 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);
}
