[GitHub] [druid] suneet-s commented on a change in pull request #10340: Fix VARIANCE aggregator comparator

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

suneet-s commented on a change in pull request #10340:
URL: https://github.com/apache/druid/pull/10340#discussion_r483061296



##########
File path: extensions-core/stats/src/main/java/org/apache/druid/query/aggregation/variance/VarianceAggregatorCollector.java
##########
@@ -60,11 +60,11 @@ public static VarianceAggregatorCollector from(ByteBuffer buffer)
   }
 
   public static final Comparator<VarianceAggregatorCollector> COMPARATOR = (o1, o2) -> {
-    int compare = Longs.compare(o1.count, o2.count);
+    int compare = Doubles.compare(o1.nvariance, o2.nvariance);

Review comment:
       I think so. I based this on the comment against the `nvariance` variable
   
   ```
   double nvariance; // sum[x-avg^2] (this is actually n times of the variance)
   ```
   
   `getVariance(isVariancePop)` looks like it divides by the count to get variance instead of nvariance.




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