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_r393480796
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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();
+ if (predicate.literal.equals(comparison.literal)) {
+ return nullable ? rexBuilder.makeCall(SqlStdOperatorTable.AND,
+ rexBuilder.makeNullLiteral(type),
+ rexBuilder.makeCall(SqlStdOperatorTable.IS_NULL, comparison.ref))
+ : rexBuilder.makeLiteral(false);
+ } else {
+ return nullable ? rexBuilder.makeCall(SqlStdOperatorTable.OR,
+ rexBuilder.makeNullLiteral(type),
+ rexBuilder.makeCall(SqlStdOperatorTable.IS_NOT_NULL,
comparison.ref))
+ : rexBuilder.makeLiteral(true);
+ }
+ }
+ return e;
+ }
+
private <C extends Comparable<C>> RexNode simplifyUsingPredicates(RexNode e,
Class<C> clazz) {
if (predicates.pulledUpPredicates.isEmpty()) {
return e;
}
+
+ if (e.getKind() == SqlKind.NOT_EQUALS) {
Review comment:
I believe the current simplification logic could be extended to also handle
the case when we have an `a!=0` predicate; and we have an `a!=0` node to
simplify.
this wasn't working before this patch; so it's entirely optional...
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