[GitHub] [calcite] ihuzenko commented on a change in pull request #1610: [CALCITE-3525] RexSimplify: eliminate redundant rex calls in OR

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ihuzenko commented on a change in pull request #1610: [CALCITE-3525] RexSimplify: eliminate redundant rex calls in OR
URL: https://github.com/apache/calcite/pull/1610#discussion_r352494626
 
 

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 File path: core/src/main/java/org/apache/calcite/rel/rules/FilterProjectTransposeRule.java
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 @@ -202,8 +202,9 @@ private RexNode simplifyFilterCondition(RexNode condition, RelOptRuleCall call)
     // 1>null evaluates to unknown and WHERE unknown behaves exactly like WHERE false
     RexSimplify simplifier =
         new RexSimplify(xBuilder, RelOptPredicateList.EMPTY, executor);
-    return RexUtil.removeNullabilityCast(
+    RexNode simplified = RexUtil.removeNullabilityCast(
         xBuilder.getTypeFactory(), simplifier.simplifyUnknownAsFalse(condition));
+    return simplified.isAlwaysFalse() ? condition : simplified;
 
 Review comment:
   Hi @danny0405 , without the check, tree may contain Filter with false condition, so then implementors (like Elasticsearch or MongoDB adapters) can't provide implementation for such Filter. The hidden issue was always there, just became visible now, after such simplification actually happened in tests. 

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