You are viewing a plain text version of this content. The canonical link for it is here.
Posted to dev@hive.apache.org by "Lefty Leverenz (JIRA)" <ji...@apache.org> on 2014/12/04 02:28:13 UTC
[jira] [Commented] (HIVE-6430) MapJoin hash table has large memory
overhead
[ https://issues.apache.org/jira/browse/HIVE-6430?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14233769#comment-14233769 ]
Lefty Leverenz commented on HIVE-6430:
--------------------------------------
Doc done, with links from the Tez parameter section:
* [Configuration Properties -- hive.mapjoin.optimized.hashtable | https://cwiki.apache.org/confluence/display/Hive/Configuration+Properties#ConfigurationProperties-hive.mapjoin.optimized.hashtable]
* [Configuration Properties -- hive.mapjoin.optimized.hashtable.wbsize | https://cwiki.apache.org/confluence/display/Hive/Configuration+Properties#ConfigurationProperties-hive.mapjoin.optimized.hashtable.wbsize]
* [Configuration Properties -- Tez | https://cwiki.apache.org/confluence/display/Hive/Configuration+Properties#ConfigurationProperties-Tez]
> 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
> 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
(v6.3.4#6332)