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https://issues.apache.org/jira/browse/HIVE-22538?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17024504#comment-17024504
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Jesus Camacho Rodriguez commented on HIVE-22538:
------------------------------------------------
+1 (pending tests)
> RS deduplication does not always enforce
> hive.optimize.reducededuplication.min.reducer
> --------------------------------------------------------------------------------------
>
> Key: HIVE-22538
> URL: https://issues.apache.org/jira/browse/HIVE-22538
> Project: Hive
> Issue Type: Bug
> Components: Physical Optimizer
> Reporter: Jesus Camacho Rodriguez
> Assignee: Krisztian Kasa
> Priority: Major
> Labels: pull-request-available
> Attachments: HIVE-22538.2.patch, HIVE-22538.3.patch,
> HIVE-22538.4.patch, HIVE-22538.5.patch, HIVE-22538.6.patch,
> HIVE-22538.6.patch, HIVE-22538.7.patch, HIVE-22538.8.patch, HIVE-22538.patch
>
> Time Spent: 1.5h
> Remaining Estimate: 0h
>
> For transactional tables, that property might be overriden to 1, which can
> lead to merging final aggregation into a single stage (hence leading to
> performance degradation). For instance, when autogather column stats is
> enabled, this can happen for the following query:
> {code}
> set hive.support.concurrency=true;
> set hive.txn.manager=org.apache.hadoop.hive.ql.lockmgr.DbTxnManager;
> EXPLAIN
> CREATE TABLE x STORED AS ORC TBLPROPERTIES('transactional'='true') AS
> SELECT * FROM SRC x CLUSTER BY x.key;
> {code}
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