mihaibudiu commented on code in PR #4646:
URL: https://github.com/apache/calcite/pull/4646#discussion_r2557883653
##########
core/src/main/java/org/apache/calcite/rex/RexSimplify.java:
##########
@@ -1153,16 +1153,15 @@ private RexNode simplifyIs(RexCall call, RexUnknownAs
unknownAs) {
return rexBuilder.makeLiteral(true);
}
if (RexUtil.isLosslessCast(a)) {
- if (!a.getType().isNullable()) {
- return rexBuilder.makeLiteral(true);
- }
- return rexBuilder.makeCall(SqlStdOperatorTable.IS_NOT_NULL,
RexUtil.removeCast(a));
+ a = RexUtil.removeCast(a);
+ // to keep this simplification, we must return IS NOT NULL(a),
+ // even if we cannot do anything else
}
if (predicates.pulledUpPredicates.contains(a)) {
return rexBuilder.makeLiteral(true);
}
if (hasCustomNullabilityRules(a.getKind())) {
- return null;
+ return rexBuilder.makeCall(SqlStdOperatorTable.IS_NOT_NULL, a);
Review Comment:
what is the difference between returning null and creating a new call?
If a is unchanged, perhaps you should return null - less wasteful
Also, please use the makeCall version which preserves the source position.
##########
core/src/main/java/org/apache/calcite/rex/RexSimplify.java:
##########
@@ -1212,16 +1211,15 @@ private RexNode simplifyIs(RexCall call, RexUnknownAs
unknownAs) {
return rexBuilder.makeLiteral(false);
}
if (RexUtil.isLosslessCast(a)) {
- if (!a.getType().isNullable()) {
- return rexBuilder.makeLiteral(false);
- }
- return rexBuilder.makeCall(SqlStdOperatorTable.IS_NULL,
RexUtil.removeCast(a));
+ a = RexUtil.removeCast(a);
+ // to keep this simplification, we must return IS NULL(a),
Review Comment:
what does it mean "keep this simplification?"
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