kgyrtkirk commented on a change in pull request #1854: [CALCITE-3852]
RexSimplify doesn't simplify NOT EQUAL predicates
URL: https://github.com/apache/calcite/pull/1854#discussion_r393474489
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File path: core/src/main/java/org/apache/calcite/rex/RexSimplify.java
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@@ -1560,18 +1560,62 @@ RexNode simplifyAnd2ForUnknownAsFalse(List<RexNode>
terms,
return RexUtil.composeConjunction(rexBuilder, terms);
}
+ private RexNode simplifyNotEqual(RexNode e) {
+ final Comparison comparison = Comparison.of(e);
+ // Check for comparison with null values
+ if (comparison == null
+ || comparison.literal.getValue() == null) {
+ return e;
+ }
+
+ for (RexNode node: predicates.pulledUpPredicates) {
+ final Comparison predicate = Comparison.of(node);
+ if (predicate == null
+ || predicate.kind != SqlKind.EQUALS
+ || predicate.literal.getValue() == null
+ || !predicate.ref.equals(comparison.ref)) {
+ continue;
+ }
+
+ // Given x=5 and x is not nullable, x!=5 can be simplified to false and
x!=3 can be
+ // simplified to true.
+ // Given x=5 and x is nullable, x!=5 can be simplified to 'null and x is
null' and x!=3 can
+ // be simplified to 'null or x is not null'.
+ final RelDataType type = comparison.ref.getType();
+ final boolean nullable = type.isNullable();
Review comment:
please remove this "nullable" boolean - and let other parts of RexSimplify
do their tricks; please note that the `UnknownAs.FALSE` case is not yet
handled; I know in case of a second invokation of `RexSimplify`; that will be
done - but ideally; RexSimplify should not be able to do any more
simplification on a result of a previously simplification.
construct the AND ; and call `simplifyUnknownAs(andNode, unknownAs)`
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