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https://issues.apache.org/jira/browse/HIVE-7832?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14110447#comment-14110447
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Prasanth J commented on HIVE-7832:
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[~gopalv] many things have changed after the initial checking. The test
failures were related to incorrect index generation. Fixed them all in this
patch. Can you take a look at this again?
> 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
>
>
> 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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