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From "Mithun Radhakrishnan (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-18608) ORC should allow selectively disabling dictionary-encoding on specified columns
Date Fri, 02 Feb 2018 01:59:00 GMT

     [ https://issues.apache.org/jira/browse/HIVE-18608?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Mithun Radhakrishnan updated HIVE-18608:
----------------------------------------
    Attachment:     (was: HIVE-18608.1-branch-2.2.patch)

> ORC should allow selectively disabling dictionary-encoding on specified columns
> -------------------------------------------------------------------------------
>
>                 Key: HIVE-18608
>                 URL: https://issues.apache.org/jira/browse/HIVE-18608
>             Project: Hive
>          Issue Type: New Feature
>          Components: ORC
>    Affects Versions: 3.0.0, 2.4.0, 2.2.1
>            Reporter: Mithun Radhakrishnan
>            Assignee: Mithun Radhakrishnan
>            Priority: Major
>         Attachments: HIVE-18608.1-branch-2.2.patch
>
>
> Just as ORC allows the choice of columns to enable bloom-filters on, it would be nice
to have a way to specify which columns {{DICTIONARY_V2}} encoding should be disabled on.
> Currently, the choice of dictionary-encoding depends on the results of sampling the first
row-stride within a stripe. If the user knows that a column's cardinality is bound to prevent
an effective dictionary, she might choose to simply disable it on just that column, and avoid
the cost of sampling in the first row-stride.



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