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Posted to gitbox@hive.apache.org by "konstantinb (via GitHub)" <gi...@apache.org> on 2026/03/23 23:26:57 UTC

Re: [PR] HIVE-29503: Prevent Join cardinality overestimation of joins with NDV(0) columns [hive]

konstantinb commented on code in PR #6356:
URL: https://github.com/apache/hive/pull/6356#discussion_r2978174554


##########
ql/src/test/results/clientpositive/llap/mapjoin_date.q.out:
##########
@@ -85,13 +85,13 @@ STAGE PLANS:
                         outputColumnNames: _col0, _col1, _col2, _col3
                         input vertices:
                           1 Map 2
-                        Statistics: Num rows: 4 Data size: 1184 Basic stats: COMPLETE Column stats: COMPLETE
+                        Statistics: Num rows: 2 Data size: 325 Basic stats: COMPLETE Column stats: NONE

Review Comment:
   at the moment. NDV of datetime/timestamp columns is not being assigned to colstats even if available. Changing that will make this estimate better; however, doing impacts over 100 .out files so perhaps doing so belongs to a separate story?



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