[
https://issues.apache.org/jira/browse/HIVE-6430?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14031334#comment-14031334
]
Lefty Leverenz commented on HIVE-6430:
--------------------------------------
We don't have a way to add parameters to the wiki automatically. Yes, they're
in the template file and I've got them on my wiki to-do list, but feel free to
take care of them yourself if you have time.
Mapjoin parameters don't have a section of their own, but they're listed
together in order of Hive release (except for a couple of hive.skewjoin.mapjoin
parameters) so these belong after hive.mapjoin.lazy.hashtable:
* [hive.mapjoin.lazy.hashtable |
https://cwiki.apache.org/confluence/display/Hive/Configuration+Properties#ConfigurationProperties-hive.mapjoin.lazy.hashtable]
> 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
> Labels: TODOC14
> 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).
--
This message was sent by Atlassian JIRA
(v6.2#6252)
