[GitHub] [calcite] danny0405 commented on a change in pull request #1322: [CALCITE-3198] ReduceExpressionsRule.FILTER_INSTANCE does not reduce 'NOT(x=a AND x=b)'

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danny0405 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_r305571886
 
 

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 File path: core/src/main/java/org/apache/calcite/rex/RexSimplify.java
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 @@ -1605,6 +1605,8 @@ private void ensureParanoidOff() {
   /** Simplifies a list of terms and combines them into an OR.
    * Modifies the list in place. */
   private RexNode simplifyOrs(List<RexNode> terms, RexUnknownAs unknownAs) {
+    // Auxiliary map to simplify cases like: X <> A OR X <> B => TRUE
+    final Map<RexNode, Comparison> notEqualsComparisonMap = new HashMap<>();
     for (int i = 0; i < terms.size(); i++) {
 
 Review comment:
   Shouldn't we invoke the `#simplifyComparison` firstly for the `OR` operator operands ? And BTW, this hashMap cache would trigger the digest computation of `RexNode`, could we have another way to identify the equivalence for RexNode ?

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