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https://issues.apache.org/jira/browse/HIVE-19326?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16523844#comment-16523844
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Ashutosh Chauhan commented on HIVE-19326:
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Is it the resultset or stats which keep changing. If stats, we can mask them.
If this doesn't repro locally at all, we shall disable this test as flaky and
deal with it on seperate jira to unblock this patch.
> stats auto gather: incorrect aggregation during UNION queries (may lead to
> incorrect results)
> ---------------------------------------------------------------------------------------------
>
> Key: HIVE-19326
> URL: https://issues.apache.org/jira/browse/HIVE-19326
> Project: Hive
> Issue Type: Bug
> Components: Statistics
> Reporter: Sergey Shelukhin
> Assignee: Zoltan Haindrich
> Priority: Critical
> Attachments: HIVE-19326.01wip01.patch, HIVE-19326.02.patch,
> HIVE-19326.03.patch, HIVE-19326.04.patch, HIVE-19326.05.patch,
> HIVE-19326.06.patch, HIVE-19326.06wip01.patch, HIVE-19326.06wip02.patch,
> HIVE-19326.06wip03.patch, HIVE-19326.06wip04.patch, HIVE-19326.06wip05.patch,
> HIVE-19326.07.patch, HIVE-19326.08.patch, HIVE-19326.09.patch
>
>
> Found when investigating the results change after converting tables to MM,
> turns out the MM result is correct but the current one is not.
> The test ends like so:
> {noformat}
> desc formatted small_alltypesorc_a;
> ANALYZE TABLE small_alltypesorc_a COMPUTE STATISTICS;
> desc formatted small_alltypesorc_a;
> insert into table small_alltypesorc_a select * from small_alltypesorc1a;
> desc formatted small_alltypesorc_a;
> {noformat}
> The results from the descs in the golden file are:
> {noformat}
> COLUMN_STATS_ACCURATE {\"BASIC_STATS\":\"true\"}
> numFiles 1
> numRows 5
> ...
> COLUMN_STATS_ACCURATE {\"BASIC_STATS\":\"true\"}
> numFiles 1
> numRows 15
> ...
> COLUMN_STATS_ACCURATE {\"BASIC_STATS\":\"true\"}
> numFiles 2
> numRows 20
> {noformat}
> Note the result change after analyze - the original nomRows is inaccurate,
> but BASIC_STATS is set to true.
> I am assuming with metadata only optimization this can produce incorrect
> results.
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