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From "Prasanth J (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HIVE-7832) Do ORC dictionary check at a finer level and preserve encoding across stripes
Date Thu, 21 Aug 2014 19:07:12 GMT
Prasanth J created HIVE-7832:
--------------------------------

             Summary: 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


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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