jcamachor commented on a change in pull request #1995:
URL: https://github.com/apache/hive/pull/1995#discussion_r579690303
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File path:
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/rules/views/HiveAggregateIncrementalRewritingRule.java
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@@ -157,17 +188,27 @@ public void onMatch(RelOptRuleCall call) {
throw new AssertionError("Found an aggregation that could not be"
+ " recognized: " + aggCall);
}
+ // According to SQL standard (and Hive) Aggregate functions eliminates
null values however operators used in
+ // elseReturn expressions returns null if one of their operands is null
+ // hence we need a null check of both operands
+ RexNode leftNull = rexBuilder.makeCall(SqlStdOperatorTable.IS_NULL,
leftRef);
+ RexNode rightNull = rexBuilder.makeCall(SqlStdOperatorTable.IS_NULL,
rightRef);
projExprs.add(rexBuilder.makeCall(SqlStdOperatorTable.CASE,
- ImmutableList.of(caseFilterCond, rightRef, elseReturn)));
+ rexBuilder.makeCall(SqlStdOperatorTable.AND, leftNull,
rightNull), rexBuilder.makeNullLiteral(leftRef.getType()),
Review comment:
I think this branch can be removed? If both are null, you will fall into
next branch, which will return rightRef (null).
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