rubenada commented on a change in pull request #1322: [CALCITE-3198]
ReduceExpressionsRule.FILTER_INSTANCE does not reduce 'NOT(x=a AND x=b)'
URL: https://github.com/apache/calcite/pull/1322#discussion_r305424810
##########
File path: core/src/main/java/org/apache/calcite/rex/RexSimplify.java
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@@ -1624,6 +1626,24 @@ private RexNode simplifyOrs(List<RexNode> terms,
RexUnknownAs unknownAs) {
continue;
}
}
+ break;
+ case NOT_EQUALS:
+ Comparison notEqualsComparison =
+ Comparison.of(term, node -> RexUtil.isReferenceOrAccess(node,
false));
Review comment:
Theoretically yes, but in practice it does not even work right now in cases
like:
`x+y = a AND x+y = b => could be simplified as FALSE, but it is not`
I think it would be too risky to try to simplify other things than
ReferenceOrAccess, but I will let other experts in this module to confirm this.
So, I'd rather keep this change simple and just enable a simplification for
the scenario described above.
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