Github user sureshsubbiah commented on a diff in the pull request:
https://github.com/apache/incubator-trafodion/pull/66#discussion_r38119659
--- Diff: core/sql/optimizer/SearchKey.cpp ---
@@ -2711,6 +2716,65 @@ void SearchKey::computeCoveredLeadingKeys()
}
}
+void SearchKey::computeFullKeyPredicates(ValueIdSet& predicates)
+{
+ // If the key column is an INDEX COLUMN, convert it into a base column
+ ValueIdList baseKeyCols;
+
+ ValueId vid;
+ const ValueIdList& keyColumns = getKeyColumns();
+ for (CollIndex i=0; i<keyColumns.entries(); i++ ) {
+ if ( keyColumns[i].getItemExpr()->getOperatorType() ==
ITM_INDEXCOLUMN )
+ vid =
((IndexColumn*)(keyColumns[i].getItemExpr()))->getDefinition();
+ else
+ vid = keyColumns[i];
+
+ baseKeyCols.insertAt(baseKeyCols.entries(), vid);
+ }
+
+ // compute the # of leading key columns covered by the key columns
+ // in the disjunct.
+ ValueIdSet columnsCoveredByKey;
+
+ vid = predicates.init();
+ for (; predicates.next(vid); predicates.advance(vid)) {
+
+ columnsCoveredByKey.clear();
+ vid.getItemExpr()->findAll(ITM_BASECOLUMN, columnsCoveredByKey,
TRUE, TRUE);
+
+ // for each vid (or predicate), check the base column list
+ for (CollIndex i=0; i<baseKeyCols.entries(); i++ ) {
+
+ NABoolean found = FALSE;
+
+ // the predicate directly refers the base column
+ if ( columnsCoveredByKey.containsTheGivenValue(baseKeyCols[i]) ) {
+ fullKeyPredicates_ += vid;
+ found = TRUE;
+ } else {
--- End diff --
I think we can get a nonlocal predicate if there is a OR (or a CASE)
For example select * from t1 a, t1 b where a.col1 = 1 OR b.col2 = 2 ;
I think this predicate will get to pushed to both scans. It may end up
being a IS NOT NULL after codegen, precodegen should see the predicate I think.
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