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Posted to dev@hive.apache.org by "Selina Zhang (JIRA)" <ji...@apache.org> on 2015/05/04 19:44:07 UTC

[jira] [Created] (HIVE-10596) Further optimize metadata only query

Selina Zhang created HIVE-10596:
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             Summary: Further optimize metadata only query 
                 Key: HIVE-10596
                 URL: https://issues.apache.org/jira/browse/HIVE-10596
             Project: Hive
          Issue Type: Improvement
          Components: Query Planning
            Reporter: Selina Zhang
            Assignee: Selina Zhang


Currently with NullScan optimizer we skip the full table scan for metadata only query. However, further step can be taken: writing metadata info to a HDFS temp file and replace the original table info with the temp table info. In this way we will not calculate the mapper number according the original files. Users like to run metadata only query for facts table; calculates splits and allocates resources for this type of query seems unnecessary.  

We had this patch and it has been running for a while. Will upload it soon.



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