[GitHub] [hive] dengzhhu653 commented on a diff in pull request #3253: HIVE-26184: COLLECT_SET with GROUP BY is very slow when some keys are highly skewed

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

dengzhhu653 commented on code in PR #3253:
URL: https://github.com/apache/hive/pull/3253#discussion_r864405523


##########
ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDAFMkCollectionEvaluator.java:
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@@ -95,11 +95,27 @@ public MkArrayAggregationBuffer() {
         throw new RuntimeException("Buffer type unknown");
       }
     }
+
+    private void reset() {
+      if (bufferType == BufferType.LIST) {
+        container.clear();

Review Comment:
   If I understand it, the `clear()` of ArrayList should have the same problem, right?



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