Github user DaveBirdsall commented on a diff in the pull request:
https://github.com/apache/incubator-trafodion/pull/218#discussion_r47155717
--- Diff: core/sql/optimizer/GroupAttr.cpp ---
@@ -327,6 +327,38 @@ void GroupAttributes::addConstraint(ItemExpr *c)
}
break;
+ case ITM_CHECK_OPT_CONSTRAINT:
+ {
+ CheckOptConstraint *cc = (CheckOptConstraint *) c;
+
+ // check existing uniqueness constraints whether they are similar
+ // and combine uniqueness constraints if possible
+ for (ValueId occ = constraints_.init();
+ constraints_.next(occ);
+ constraints_.advance(occ))
+ {
+ if (occ.getItemExpr()->getOperatorType() ==
+ ITM_CHECK_OPT_CONSTRAINT)
+ {
+ const ValueIdSet &occPreds =
+ ((CheckOptConstraint *)
occ.getItemExpr())->getCheckPreds();
+
+ if (occPreds.contains(cc->getCheckPreds()))
--- End diff --
A question about how this works (more from my own ignorance): Does
"contains" do a semantic comparison? Or just a ValueId comparison? For example,
if I code two CHECK CONSTRAINTS with predicates A < B and A < B, is the ValueId
of the '<' the same for both? And how is that accomplished? Similarly, if I
have two CHECK CONSTRAINTS with predicates A < B and B > A, will the second be
normalized back to A < B and get the same ValueId?
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