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From "Prasanth J (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-7832) Do ORC dictionary check at a finer level and preserve encoding across stripes
Date Wed, 27 Aug 2014 17:18:01 GMT

     [ https://issues.apache.org/jira/browse/HIVE-7832?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Prasanth J updated HIVE-7832:
-----------------------------

    Attachment: HIVE-7832.7.patch

vectorization_part_project.q seems to pass in latest trunk. Uploaded the .6 patch with different
name just to make sure vectorization_part_project.q is passing now.

> 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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