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https://issues.apache.org/jira/browse/HIVE-26673?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Simhadri Govindappa resolved HIVE-26673.
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Fix Version/s: 4.0.0
Resolution: Fixed
> Incorrect row count when vectorisation is enabled
> -------------------------------------------------
>
> Key: HIVE-26673
> URL: https://issues.apache.org/jira/browse/HIVE-26673
> Project: Hive
> Issue Type: Bug
> Components: Hive
> Affects Versions: 4.0.0-alpha-2
> Reporter: Simhadri Govindappa
> Priority: Major
> Fix For: 4.0.0
>
>
> Repro:
> {noformat}
> select count(*) from
> (SELECT T0.plant_no,
> T0.part_chain,
> T0.part_new,
> T0.part_no
> FROM dm_ads_dims_prod.cloudera_test3 T0
> LEFT JOIN
> (SELECT T0.plant_no,
> T0.part_chain
> FROM
> (SELECT T0.plant_no,
> T0.part_chain,
> count( *) AS ct
> FROM dm_ads_dims_prod.cloudera_test3 T0
> WHERE purchase_pos = pos
> GROUP BY T0.plant_no,
> T0.part_chain) T0
> WHERE ct = 2 ) T1 ON T0.plant_no = T1.plant_no
> AND T0.part_chain = T1.part_chain
> WHERE T0.purchase_pos = T0.pos
> AND (T1.part_chain IS NULL
> OR (T1.part_chain IS NOT NULL
> AND T0.fd = 1)) ) s;
> {noformat}
> Run the query with the following settings on the repro cluster a few times
> {code:java}
> set hive.query.results.cache.enabled=false;
> set hive.compute.query.using.stats=false;
> set hive.auto.convert.join=true;
> {code}
> and the results was
> {code:java}
> 2682424
> 2682426
> 2682425{code}
>
> Then turn off {{hive.auto.convert.join}}
> {code:java}
> set hive.query.results.cache.enabled=false;
> set hive.compute.query.using.stats=false;
> set hive.auto.convert.join=false;
> {code}
> and the result was always *2682420*
> Analyzing the plans with hive.auto.convert.join enabled vs disabled, the
> difference is the type of join Map vs Merge.
> Additionally, vectorization also plays a role when turned off the result
> became good:
> {code:java}
> SET hive.vectorized.execution.enabled=false;
> {code}
> It is also just a workaround and has negative impact on performance this
> should help us narrow down where to find the cause of the issue.
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