hive-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Lefty Leverenz (JIRA)" <>
Subject [jira] [Commented] (HIVE-6429) MapJoinKey has large memory overhead in typical cases
Date Sat, 22 Feb 2014 06:42:19 GMT


Lefty Leverenz commented on HIVE-6429:

*hive.mapjoin.optimized.keys* needs a definition ... but I'm not sure where, because that
depends on the state of HIVE-6037 which will put the config param definitions into
and then generate hive-default.xml.template from

See comment on HIVE-6455 for details (but note that HIVE-6037 has been reopened):  [17 Feb
2014 22:26 comment |].

So if this commits before HIVE-6037, *hive.mapjoin.optimized.keys* should be documented in
hive-default.xml.template as usual but if it commits after HIVE-6037 a definition should be
added to the patched version of  In any case, I'll add it to the wiki with
a release note.

> MapJoinKey has large memory overhead in typical cases
> -----------------------------------------------------
>                 Key: HIVE-6429
>                 URL:
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: Sergey Shelukhin
>            Assignee: Sergey Shelukhin
>         Attachments: HIVE-6429.01.patch, HIVE-6429.02.patch, HIVE-6429.03.patch, HIVE-6429.WIP.patch,
> The only thing that MJK really needs it hashCode and equals (well, and construction),
so there's no need to have array of writables in there. Assuming all the keys for a table
have the same structure, for the common case where keys are primitive types, we can store
something like a byte array combination of keys to reduce the memory usage. Will probably
speed up compares too.

This message was sent by Atlassian JIRA

View raw message