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Posted to issues@tajo.apache.org by "hyoungjunkim (JIRA)" <ji...@apache.org> on 2014/03/19 02:43:42 UTC

[jira] [Commented] (TAJO-691) HashJoin or HashAggregation is too slow if there is many unique keys

    [ https://issues.apache.org/jira/browse/TAJO-691?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13940054#comment-13940054 ] 

hyoungjunkim commented on TAJO-691:
-----------------------------------

I suggest MapDB's LongHashMap. Please check the bellow site.

http://www.mapdb.org/
http://kotek.net/blog/3G_map

> HashJoin or HashAggregation is too slow if there is many unique keys
> --------------------------------------------------------------------
>
>                 Key: TAJO-691
>                 URL: https://issues.apache.org/jira/browse/TAJO-691
>             Project: Tajo
>          Issue Type: Improvement
>            Reporter: hyoungjunkim
>
> HashJoin or HashAggregation is too slow if there is many unique keys.
> Java's native Map is inefficient  to handle many items. In case more than 1 million items in HashMap, Adding 10000 items takes more than 7 ~ 10 seconds.   
> This should be improved.



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