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From "Josh Wills (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CRUNCH-216) Transpose arguments in MapsideJoinStrategy.join
Date Mon, 19 Aug 2013 15:50:48 GMT

    [ https://issues.apache.org/jira/browse/CRUNCH-216?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13743926#comment-13743926
] 

Josh Wills commented on CRUNCH-216:
-----------------------------------

I don't know that I have a great way of handling it. Just spitballing this: join() could,
by default, use the getSize() methods on the left and right table to decide which of the two
was smaller, and we could add an argument or have another method that would allow the developer
to explicitly specify the ordering, something like joinSmallerToLarger(). It's the least bad
way I see to make all of the different join() methods consistent with each other, but it involves
making the Crunch libs more clever than I generally like them to be.
                
> Transpose arguments in MapsideJoinStrategy.join
> -----------------------------------------------
>
>                 Key: CRUNCH-216
>                 URL: https://issues.apache.org/jira/browse/CRUNCH-216
>             Project: Crunch
>          Issue Type: Improvement
>            Reporter: Gabriel Reid
>
> The MapsideJoinStrategy currently specifies that the smaller table in the join (i.e.
the table to be replicated and loaded in memory) should be on the right-hand side of the join.
> This is the opposite of what is done in all other join strategies, making it impossible
to just switch out another join strategy for a MapsideJoinStrategy. The MapsideJoinStrategy
could be brought in line with the other JoinStrategies to expect the smaller of two tables
to be provided as the left-side table.

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