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From "Gabriel Reid (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CRUNCH-215) Add BloomFilterJoinStrategy
Date Mon, 10 Jun 2013 17:18:20 GMT

    [ https://issues.apache.org/jira/browse/CRUNCH-215?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13679644#comment-13679644
] 

Gabriel Reid commented on CRUNCH-215:
-------------------------------------

Ok, got it, thanks for the explanation. In any case, the code for the toBytes method is written
now, so it should be a simple thing to move it to the PType implementation classes. It would
probably also be worth having optimized versions for primitive values, instead of writing
them to an Avro/Writable first to get the bytes representation. But yeah, that's for another
JIRA.
                
> Add BloomFilterJoinStrategy
> ---------------------------
>
>                 Key: CRUNCH-215
>                 URL: https://issues.apache.org/jira/browse/CRUNCH-215
>             Project: Crunch
>          Issue Type: New Feature
>            Reporter: Gabriel Reid
>            Assignee: Gabriel Reid
>         Attachments: CRUNCH-215.patch
>
>
> Bloom filters can be very effective for pre-filtering one side of a join when one side
of the join has a small subset of the keys of the other side (i.e. there are many keys on
one side that will not be joined).
> The Bloom filter can be built up based on the keys of one side of the join (the side
with fewer keys), and then can be applied as a filter to the other side of the join before
it is sent through the shuffle and reduce phases.

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