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From "Pradeep Kamath (JIRA)" <j...@apache.org>
Subject [jira] Updated: (PIG-554) Fragment Replicate Join
Date Wed, 07 Jan 2009 22:42:44 GMT

     [ https://issues.apache.org/jira/browse/PIG-554?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Pradeep Kamath updated PIG-554:
-------------------------------

    Attachment: PIG-554-v4.patch

Changes in new patch (attached):
1) The HashMap now has (tuple, List<Tuple>) to address the concern that Bag would be
worse spacewise than a List<Tuple>. BagFactory now has a method newDefaultBag(List<Tuple>)
which will create a DefaultDataBag out of the List<Tuple> by taking ownership of the
list and without copying the elements. This way in POFRJoin.getNext() we can create a bag
out of the List<Tuple> without much overhead.
2) Added back the unit test - TestFRJoin - the change in this file is to use Util.createInputFile()
 to create input file for the tests on the minicluster DFS rather than local file system.
It used Util.deleteFile() to delete the file before after each test run.

> Fragment Replicate Join
> -----------------------
>
>                 Key: PIG-554
>                 URL: https://issues.apache.org/jira/browse/PIG-554
>             Project: Pig
>          Issue Type: New Feature
>    Affects Versions: types_branch
>            Reporter: Shravan Matthur Narayanamurthy
>            Assignee: Shravan Matthur Narayanamurthy
>             Fix For: types_branch
>
>         Attachments: frjofflat.patch, frjofflat1.patch, PIG-554-v3.patch, PIG-554-v4.patch
>
>
> Fragment Replicate Join(FRJ) is useful when we want a join between a huge table and a
very small table (fitting in memory small) and the join doesn't expand the data by much. The
idea is to distribute the processing of the huge files by fragmenting it and replicating the
small file to all machines receiving a fragment of the huge file. Because of the availability
of the entire small file, the join becomes a trivial task without needing any break in the
pipeline. Exhaustive test have done to determine the improvement we get out of FRJ. Here are
the details: http://wiki.apache.org/pig/PigFRJoin
> The patch makes changes to parts of the code where new operators are introduced. Currently,
when a new operator is introduced, its alias is not set. For schema computation I have modified
this behaviour to set the alias of the new operator to that of its predecessor. The logical
side of the patch mimics the cogroup behavior as join syntax closely resembles that of cogroup.
Currently, this patch doesn't have support for joins other than inner joins. The rest of the
code has been documented.

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