[jira] [Created] (HIVE-13232) Aggressively drop compression buffers in ORC OutStreams

["Owen O'Malley (JIRA)" <ji...@apache.org>]

Owen O'Malley created HIVE-13232:
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             Summary: Aggressively drop compression buffers in ORC OutStreams
                 Key: HIVE-13232
                 URL: https://issues.apache.org/jira/browse/HIVE-13232
             Project: Hive
          Issue Type: Bug
          Components: ORC
            Reporter: Owen O'Malley
            Assignee: Owen O'Malley


In Hive 0.11, when ORC's OutStream's were flushed they dropped all of the their buffers. In the patch for HIVE-4342, we inadvertently changed that behavior so that one of the buffers is held on to. For queries with a lot of writers and thus under significant memory pressure this can have a significant impact on the memory usage. 

Note that "hive.optimize.sort.dynamic.partition" avoids this problem by sorting on the dynamic partition key and thus only a single ORC writer is open at once. This will use memory more effectively and avoid creating ORC files with very small stripes, which will produce better downstream performance.



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