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Posted to dev@pig.apache.org by "Alan Gates (JIRA)" <ji...@apache.org> on 2009/02/06 00:03:59 UTC
[jira] Assigned: (PIG-460) PERFORMANCE: Order by done in 3 MR
jobs, could be done in 2
[ https://issues.apache.org/jira/browse/PIG-460?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Alan Gates reassigned PIG-460:
------------------------------
Assignee: Pradeep Kamath (was: Amir Youssefi)
Assigning to Pradeep for review.
> PERFORMANCE: Order by done in 3 MR jobs, could be done in 2
> ------------------------------------------------------------
>
> Key: PIG-460
> URL: https://issues.apache.org/jira/browse/PIG-460
> Project: Pig
> Issue Type: Bug
> Affects Versions: types_branch
> Reporter: Alan Gates
> Assignee: Pradeep Kamath
> Fix For: types_branch
>
> Attachments: sampler.patch, sampler2.patch
>
>
> Currently order by is done in three MR jobs:
> job 1: read data in whatever loader the user requests, store using BinStorage
> job 2: load using RandomSampleLoader, find quantiles
> job 3: load data again and sort
> It is done this way because RandomSampleLoader extends BinStorage, and so needs the data in that format to read it.
> If the logic in RandomSampleLoader was made into an operator instead of being in a loader then jobs 1 and 2 could be merged. On average job 1 takes about 15% of the time of an order by script.
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