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From "Owen O'Malley (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-4579) Create a SARG interface for RecordReaders
Date Tue, 21 May 2013 21:44:20 GMT

    [ https://issues.apache.org/jira/browse/HIVE-4579?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13663437#comment-13663437
] 

Owen O'Malley commented on HIVE-4579:
-------------------------------------

Another alternative is to put the expression into disjunctive normal form:

{code}
SARG: ALTERNATIVE | ALTERNATIVE or SARG
ALTERNATIVE: COND | COND and ALTERNATIVE
{code}

that forces the or conditions to be top level operators. Of course the most effective filters
will have a very small number of alternatives since the effectiveness decreases rapidly as
the number of alternatives increases.

                
> Create a SARG interface for RecordReaders
> -----------------------------------------
>
>                 Key: HIVE-4579
>                 URL: https://issues.apache.org/jira/browse/HIVE-4579
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: Owen O'Malley
>            Assignee: Owen O'Malley
>
> I think we should create a SARG (http://en.wikipedia.org/wiki/Sargable) interface for
RecordReaders. For a first pass, I'll create an API that uses the value stored in hive.io.filter.expr.serialized.
> The desire is to define an simpler interface that the direct AST expression that is provided
by hive.io.filter.expr.serialized so that the code to evaluate expressions can be generalized
instead of put inside a particular RecordReader.

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