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From "Gopal V (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-7832) Do ORC dictionary check at a finer level and preserve encoding across stripes
Date Fri, 29 Aug 2014 22:57:53 GMT

    [ https://issues.apache.org/jira/browse/HIVE-7832?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14116002#comment-14116002
] 

Gopal V commented on HIVE-7832:
-------------------------------

I left some minor comments on RB - the extra configuration variable is not really a user-friendly
feature and needs to be removed.

Possibly provide a hard enable/disable config variable and nothing more around this.

> Do ORC dictionary check at a finer level and preserve encoding across stripes
> -----------------------------------------------------------------------------
>
>                 Key: HIVE-7832
>                 URL: https://issues.apache.org/jira/browse/HIVE-7832
>             Project: Hive
>          Issue Type: Improvement
>    Affects Versions: 0.14.0
>            Reporter: Prasanth J
>            Assignee: Prasanth J
>         Attachments: HIVE-7832.1.patch, HIVE-7832.2.patch, HIVE-7832.3.patch, HIVE-7832.4.patch,
HIVE-7832.5.patch, HIVE-7832.6.patch, HIVE-7832.7.patch
>
>
> Currently ORC dictionary check happens while writing the stripe. Just before writing
stripe if ratio of dictionary entries to total non-null rows is greater than threshold then
the dictionary is discarded. Also, the decision of using dictionary or not is preserved across
stripes. This sometimes leads to costly insertion cost of O(logn) for each stripes when there
are too many distinct keys.



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