[GitHub] [druid] gianm commented on a change in pull request #10316: Optimize InDimFilter hashCode calculation

[GitBox <gi...@apache.org>]

gianm commented on a change in pull request #10316:
URL: https://github.com/apache/druid/pull/10316#discussion_r476197783



##########
File path: processing/src/main/java/org/apache/druid/query/filter/InDimFilter.java
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@@ -382,7 +386,7 @@ public boolean equals(Object o)
   @Override
   public int hashCode()
   {
-    return Objects.hash(values, dimension, extractionFn, filterTuning);
+    return Objects.hash(values.size(), dimension, extractionFn, filterTuning);

Review comment:
       Maybe use the size and the first few values?
   
   It's easy to imagine situations where the extra collisions from only checking size are a problem, and it's tough to imagine situations where the perf impact of adding[the first few values is going to be big. So it seems like a good idea.
   
   Please also include a comment about the rationale for the nonstandard hashCode impl. It'd be good to link to this PR.




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