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From "Ashutosh Chauhan (JIRA)" <>
Subject [jira] [Commented] (HIVE-3784) de-emphasize mapjoin hint
Date Mon, 10 Dec 2012 06:41:21 GMT


Ashutosh Chauhan commented on HIVE-3784:

I agree. In general,
more config = more confusion for user to use it.
more config = more confusion for developer to maintain code.
> de-emphasize mapjoin hint
> -------------------------
>                 Key: HIVE-3784
>                 URL:
>             Project: Hive
>          Issue Type: Improvement
>          Components: Query Processor
>            Reporter: Namit Jain
>            Assignee: Namit Jain
> has been around for a long time, and is pretty stable.
> When mapjoin hint was created, the above parameter did not exist.
> The only reason for the user to specify a mapjoin currently is if they want
> it to be converted to a bucketed-mapjoin or a sort-merge bucketed mapjoin.
> Eventually, that should also go away, but that may take some time to stabilize.
> There are many rules in SemanticAnalyzer to handle the following trees:
> ReduceSink -> MapJoin
> Union      -> MapJoin
> MapJoin    -> MapJoin
> This should not be supported anymore. In any of the above scenarios, the
> user can get the mapjoin behavior by setting to true
> and not specifying the hint. This will simplify the code a lot.
> What does everyone think ?

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