Github user zellerh commented on a diff in the pull request:
https://github.com/apache/incubator-trafodion/pull/1051#discussion_r110733170
--- Diff: core/sql/optimizer/RelExpr.cpp ---
@@ -9121,38 +9090,85 @@ NABoolean Scan::updateableIndex(IndexDesc *idx)
{
ItemExpr *updateCol = colUpdated[i].getItemExpr();
CMPASSERT(updateCol->getOperatorType() == ITM_BASECOLUMN);
-
for (CollIndex j = 0; j < indexKey.entries(); j++)
{
ItemExpr *keyCol = indexKey[j].getItemExpr();
-
- ItemExpr *baseCol =
((IndexColumn*)keyCol)->getDefinition().getItemExpr();
+ ItemExpr *baseCol =
+ ((IndexColumn*)keyCol)->getDefinition().getItemExpr();
CMPASSERT(baseCol->getOperatorType() == ITM_BASECOLUMN);
-
- // QSTUFF
- if (getGroupAttr()->isEmbeddedUpdate()){
- if (((BaseColumn*)updateCol)->getColNumber() ==
+ if (((BaseColumn*)updateCol)->getColNumber() ==
((BaseColumn*)baseCol)->getColNumber())
- return FALSE;
- }
- // QSTUFF
+ return FALSE;
+ }
+ }
+ return TRUE;
+} // Scan::updateableIndex
+
+NABoolean Scan::requiresHalloweenForUpdateUsingIndexScan()
+{
+
+ // Returns TRUE if any non clustering index can be used for a scan
+ // during an UPDATE and a key column of that index is in the SET
+ // clause of the update. If this method returns TRUE we will use a
+ // sort node to prevent the "Halloween Update Problem".
+ //
- if ((NOT(idx->isUniqueIndex() || idx->isClusteringIndex()))
- ||
- (CmpCommon::getDefault(UPDATE_CLUSTERING_OR_UNIQUE_INDEX_KEY) ==
DF_OFF))
+ // preds are in RangeSpec form
+ ValueIdSet preds = getSelectionPredicates();
+ const ValueIdList colUpdated = getTableDesc()->getColUpdated();
+ const LIST(IndexDesc *) & ixlist = getTableDesc()->getIndexes();
+
+ if ((colUpdated.entries() == 0) || (preds.entries() == 0) ||
+ (ixlist.entries() == 1) || // this is the clustering index
+ (CmpCommon::getDefault(UPDATE_CLUSTERING_OR_UNIQUE_INDEX_KEY)
+ == DF_AGGRESSIVE)) // this setting means no Halloween protection
+ return FALSE;
+
+ if (CmpCommon::getDefault(RANGESPEC_TRANSFORMATION) == DF_ON)
+ {
+ ValueIdList selectionPredList(preds);
+ ItemExpr *inputItemExprTree =
+ selectionPredList.rebuildExprTree(ITM_AND,FALSE,FALSE);
+ ItemExpr * resultOld = revertBackToOldTree(STMTHEAP,
+ inputItemExprTree);
+ preds.clear();
+ resultOld->convertToValueIdSet(preds, NULL, ITM_AND);
+ doNotReplaceAnItemExpressionForLikePredicates(resultOld,preds,
+ resultOld);
+ }
+ for (CollIndex indexNo = 0; indexNo < ixlist.entries(); indexNo++)
+ {
+ IndexDesc *idx = ixlist[indexNo];
+ if (idx->isClusteringIndex() ||
+ (idx->isUniqueIndex() &&
+ (CmpCommon::getDefault(UPDATE_CLUSTERING_OR_UNIQUE_INDEX_KEY)
+ == DF_ON)))
+ continue ; // skip this idesc
+
+ const ValueIdList indexKey = idx->getIndexKey();
+ // Determine if the columns being updated are key columns. Each key
+ // column being updated must have an associated equality clause in
+ // the WHERE clause of the UPDATE for it to be used.
+ for (CollIndex i = 0; i < colUpdated.entries(); i++)
--- End diff --
I don't quite understand this comment and the logic below. The existing
method, Scan::updateableIndex(), allows an index if it is a) a unique index or
b) has a unique predicate on its key or c) has an equals predicate on all the
index columns of a non-unique index. Do you want to achieve something different
here?
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
