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https://issues.apache.org/jira/browse/PIG-2573?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Travis Crawford updated PIG-2573:
---------------------------------
Attachment: PIG-2573_get_size_from_stats_if_possible.diff
Patch has been updated to get the size from loader-reported statistics, if
possible. If not possible, the current behavior remains.
> Automagically setting parallelism based on input file size does not work with
> HCatalog
> --------------------------------------------------------------------------------------
>
> Key: PIG-2573
> URL: https://issues.apache.org/jira/browse/PIG-2573
> Project: Pig
> Issue Type: Bug
> Reporter: Travis Crawford
> Assignee: Travis Crawford
> Attachments: PIG-2573_get_size_from_stats_if_possible.diff,
> PIG-2573_move_getinputbytes_to_loadfunc.diff
>
>
> PIG-2334 was helpful in understanding this issue. Short version is input file
> size is only computed if the path begins with a whitelisted prefix, currently:
> * /
> * hdfs:
> * file:
> * s3n:
> As HCatalog locations use the form {{dbname.tablename}} the input file size
> is not computed, and the size-based parallelism optimization breaks.
> DETAILS:
> I discovered this issue comparing two runs on the same script, one loading
> regular HDFS paths, and one with HCatalog db.table names. I just happened to
> notice the "Setting number of reducers" line difference.
> {code:title=Loading HDFS files reducers is set to 99}
> 2012-03-08 01:33:56,522 [main] INFO
> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.JobControlCompiler
> - BytesPerReducer=1000000000 maxReducers=999 totalInputFileSize=98406674162
> 2012-03-08 01:33:56,522 [main] INFO
> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.JobControlCompiler
> - Neither PARALLEL nor default parallelism is set for this job. Setting
> number of reducers to 99
> {code}
> {code:title=Loading with an HCatalog db.table name}
> 2012-03-08 01:06:02,283 [main] INFO
> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.JobControlCompiler
> - BytesPerReducer=1000000000 maxReducers=999 totalInputFileSize=0
> 2012-03-08 01:06:02,283 [main] INFO
> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.JobControlCompiler
> - Neither PARALLEL nor default parallelism is set for this job. Setting
> number of reducers to 1
> {code}
> Possible fix: Pig should just ask the loader for the size of its inputs
> rather than special-casing certain location types.
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