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Posted to dev@crunch.apache.org by "Gabriel Reid (JIRA)" <ji...@apache.org> on 2012/09/20 21:13:08 UTC

[jira] [Resolved] (CRUNCH-72) Cartesian#cross loads all data in memory per parallel mapper

     [ https://issues.apache.org/jira/browse/CRUNCH-72?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Gabriel Reid resolved CRUNCH-72.
--------------------------------

       Resolution: Fixed
    Fix Version/s: 0.4.0

Committed to master
                
> Cartesian#cross loads all data in memory per parallel mapper
> ------------------------------------------------------------
>
>                 Key: CRUNCH-72
>                 URL: https://issues.apache.org/jira/browse/CRUNCH-72
>             Project: Crunch
>          Issue Type: Bug
>            Reporter: Gabriel Reid
>            Assignee: Gabriel Reid
>             Fix For: 0.4.0
>
>
> Cartesian#cross currently uses the PTable#cogroup method to join two sets of data together; this results in all data from both sides of the join being loaded in memory at one time. This can be a real problem with cartesian joins because of the quantity of data being joined.
> Using PTable#join instead of PTable#cogroup will reduce the memory usage by 50%, which can be the difference between a cartesian join working or failing with an OOME.

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