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From "Owen O'Malley (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-9166) Place an upper bound for SARG CNF conversion
Date Thu, 18 Dec 2014 22:22:13 GMT

    [ https://issues.apache.org/jira/browse/HIVE-9166?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14252406#comment-14252406
] 

Owen O'Malley commented on HIVE-9166:
-------------------------------------

+1 LGTM

You probably should add a test case where there is something other than the large CNF.

something like (and leaf-1 (or ...))

You should end up with leaf-1 as your final expression.



> Place an upper bound for SARG CNF conversion
> --------------------------------------------
>
>                 Key: HIVE-9166
>                 URL: https://issues.apache.org/jira/browse/HIVE-9166
>             Project: Hive
>          Issue Type: Bug
>    Affects Versions: 0.14.0, 0.15.0
>            Reporter: Prasanth Jayachandran
>            Assignee: Prasanth Jayachandran
>              Labels: orcfile
>         Attachments: HIVE-9166.1.patch, HIVE-9166.2.patch
>
>
> SARG creation in ORC, applies several optimizations to expression tree. In that CNF conversion
is an exponential algorithm as it finds all combinations of expressions when converting from
OR of AND form to AND of OR form (CNF). We need an upper bound for this algorithm to prevent
it from running for long time and generating huge combinations list.



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