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From "Chao Shi (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CRUNCH-368) TupleWritable.Comparator
Date Sat, 22 Mar 2014 03:03:42 GMT

    [ https://issues.apache.org/jira/browse/CRUNCH-368?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13943867#comment-13943867
] 

Chao Shi commented on CRUNCH-368:
---------------------------------

Before this patch, no WritableComparator is registered, so a default implementation will be
used, which is deserializing both keys and compare the objects. The registered comparator
acts as a kind of optimization. You can see examples in Text/Text.Comparator or IntWritable/IntWritable.Comparator.

> TupleWritable.Comparator
> ------------------------
>
>                 Key: CRUNCH-368
>                 URL: https://issues.apache.org/jira/browse/CRUNCH-368
>             Project: Crunch
>          Issue Type: Improvement
>          Components: Core
>    Affects Versions: 0.8.3
>            Reporter: Chao Shi
>            Assignee: Chao Shi
>         Attachments: crunch-368.patch
>
>
> This patch should improve comparison performance on TupleWritables. It saves the deserialization
overhead. It is particularly useful when the input tuple are large, e.g. contains long strings.
> Please note that this changes the binary format of TupleWritable. It adds a var-int indicating
size of field after each type code. This is a limitation of the writable system. We do not
know the size of each field until fully desalinizing it. 



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