kgyrtkirk 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_r307614411
##########
File path: core/src/main/java/org/apache/calcite/rex/RexSimplify.java
##########
@@ -1624,6 +1630,47 @@ private RexNode simplifyOrs(List<RexNode> terms,
RexUnknownAs unknownAs) {
continue;
}
}
+ break;
+ case NOT_EQUALS:
+ final Comparison notEqualsComparison =
+ Comparison.of(term, node -> RexUtil.isReferenceOrAccess(node,
false));
+ if (notEqualsComparison != null) {
+ // We are dealing with a X<>A term, check if we saw before another
NOT_EQUALS involving X
+ final RexNode prevNotEquals =
notEqualsComparisonMap.get(notEqualsComparison.ref);
+ if (prevNotEquals == null) {
+ // This is the first NOT_EQUALS involving X, put it in the map
+ notEqualsComparisonMap.put(notEqualsComparison.ref, term);
+ } else {
+ // There is already in the map another NOT_EQUALS involving X:
+ // - if it is already an IS_NOT_NULL: it was already simplified,
ignore this term
+ // - if it is not an IS_NOT_NULL (i.e. it is a NOT_EQUALS):
check comparison values
+ if (prevNotEquals.getKind() != SqlKind.IS_NOT_NULL) {
+ final Comparable comparable1 =
notEqualsComparison.literal.getValue();
+ //noinspection ConstantConditions
+ final Comparable comparable2 = Comparison.of(
+ prevNotEquals, node -> RexUtil.isReferenceOrAccess(node,
false))
+ .literal.getValue();
+ //noinspection unchecked
+ if (comparable1.compareTo(comparable2) != 0) {
+ // We found: X <> A OR X <> B
+ if (unknownAs == RexUnknownAs.TRUE ||
!term.getType().isNullable()) {
Review comment:
* you should choose one path or the other - but not both...if you go the
generic way then let other parts of `RexSimplify` do the work; by replacing the
term with the result of: `simplify( ref IS NOT NULL OR NULL )`
* ref IS NOT NULL will return false when the original expression should be
null - please also add a testcase for this
```
checkSimplify(
or(
ne(vInt(), literal(1)),
ne(vInt(), literal(2))),
"...");
```
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