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Posted to dev@hive.apache.org by "Mithun Radhakrishnan (JIRA)" <ji...@apache.org> on 2018/02/02 01:56:00 UTC

[jira] [Created] (HIVE-18608) ORC should allow selectively disabling dictionary-encoding on specified columns

Mithun Radhakrishnan created HIVE-18608:
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             Summary: 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


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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