Misha Dmitriev commented on HIVE-6430:

Thank you [~akolb]! This is nice work of the kind I wish I can do more :)

> 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
>            Assignee: Sergey Shelukhin
>            Priority: Major
>             Fix For: 0.14.0
>         Attachments: HIVE-6430.01.patch, HIVE-6430.02.patch, 
> HIVE-6430.03.patch, HIVE-6430.04.patch, HIVE-6430.05.patch, 
> HIVE-6430.06.patch, HIVE-6430.07.patch, HIVE-6430.08.patch, 
> HIVE-6430.09.patch, HIVE-6430.10.patch, HIVE-6430.11.patch, 
> HIVE-6430.12.patch, HIVE-6430.12.patch, HIVE-6430.13.patch, 
> HIVE-6430.14.patch, HIVE-6430.patch
> 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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