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From "Sriranjan Manjunath (JIRA)" <j...@apache.org>
Subject [jira] Commented: (PIG-1143) Poisson Sample Loader should compute the number of samples required only once
Date Thu, 10 Dec 2009 23:32:18 GMT

    [ https://issues.apache.org/jira/browse/PIG-1143?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12789023#action_12789023
] 

Sriranjan Manjunath commented on PIG-1143:
------------------------------------------

The file size in the documentation refers to the size on disk. In order to account for compression,
encoding etc. a configurable parameter - pig.inputfile.conversionfactor is provided. I agree
that this cannot be set to a good value for compressed data. It is just a guidance. The implications
of setting it to a bad value are minimal - we will end up sampling little more than the required
number of samples (unless you set it to a fraction).

> Poisson Sample Loader should compute the number of samples required only once
> -----------------------------------------------------------------------------
>
>                 Key: PIG-1143
>                 URL: https://issues.apache.org/jira/browse/PIG-1143
>             Project: Pig
>          Issue Type: Bug
>            Reporter: Sriranjan Manjunath
>            Assignee: Sriranjan Manjunath
>
> The current poisson sampler forces each of the maps to compute the sample number. This
is redundant and causes issues when a large directory is specified in the join. The sampler
should be changed to calculate the sample count only once and this information should be shared
with the remaining mappers.

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