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Posted to dev@hive.apache.org by "Sergey Shelukhin (JIRA)" <ji...@apache.org> on 2014/02/14 05:35:19 UTC

[jira] [Created] (HIVE-6430) HIVE-6429 - MapJoin hash table has large memory overhead

Sergey Shelukhin created HIVE-6430:
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             Summary:  HIVE-6429 - MapJoin hash table has large memory overhead
                 Key: HIVE-6430
                 URL: https://issues.apache.org/jira/browse/HIVE-6430
             Project: Hive
          Issue Type: Improvement
            Reporter: Sergey Shelukhin


Right now, in some queries, I see that storing e.g. 4 ints (2 for key and 2 for row) can take several hundred bytes, which is ridiculous. I am reducing the size of MJKey and MJRowContainer in other jiras, but in general we don't need to have java hash table there.  We can either use primitive-friendly hashtable like the one from HPPC (Apache-licenced), or some variation, to map primitive keys to single row storage structure without an object per row (similar to vectorization).



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