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https://issues.apache.org/jira/browse/HIVE-7832?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14118736#comment-14118736
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Lefty Leverenz commented on HIVE-7832:
--------------------------------------
Doc note: This adds configuration parameter
*hive.orc.row.index.stride.dictionary.check* to HiveConf.java, so it needs to
be documented in the wiki for 0.14.0.
* [Configuration Properties -- ORC File Format |
https://cwiki.apache.org/confluence/display/Hive/Configuration+Properties#ConfigurationProperties-ORCFileFormat]
> 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
> Labels: TODOC14
> Fix For: 0.14.0
>
> 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,
> HIVE-7832.8.patch, HIVE-7832.9.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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