Jesus Camacho Rodriguez created HIVE-22538:
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             Summary: 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
            Reporter: Jesus Camacho Rodriguez
            Assignee: Jesus Camacho Rodriguez


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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