[GitHub] [calcite] libenchao commented on a diff in pull request #3143: [CALCITE-5639] eliminate IS_NOT_NULL check if LIKE expression on the same column is present

["libenchao (via GitHub)" <gi...@apache.org>]

libenchao commented on code in PR #3143:
URL: https://github.com/apache/calcite/pull/3143#discussion_r1168159208


##########
core/src/main/java/org/apache/calcite/rex/RexSimplify.java:
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@@ -2599,6 +2602,22 @@ default boolean allowedInOr(RelOptPredicateList predicates) {
     }
   }
 
+  /**
+   * Visitor which finds all inputs used by an expressions.
+   */
+  private static class VariableCollector extends RexVisitorImpl<Void> {
+    private final Set<RexInputRef> refs = new LinkedHashSet<>();

Review Comment:
   I have the same feeling with @asolimando, usually a `LinkedHashSet` would make me wonder what's its purpose to use it instead of a `HashSet`, which will increase the cost of understanding.
   
   If we have a reason, we'd better write it into the comment. Else, I would prefer to use the most general one for the above reason. WDYT?



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