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https://issues.apache.org/jira/browse/PIG-627?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Richard Ding updated PIG-627:
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    Attachment: multiquery-phase2_0313.patch

 This patch completes the phase 2 development as sepecified in the document 
http://wiki.apache.org/pig/PigMultiQueryPerformanceSpecification:
       # Allow multiple stores in single job
       # Merge multiple plans into the split operator
       # Terminate all but one with stores

This patch is for the multi query branch.




> PERFORMANCE: multi-query optimization
> -------------------------------------
>
>                 Key: PIG-627
>                 URL: https://issues.apache.org/jira/browse/PIG-627
>             Project: Pig
>          Issue Type: Improvement
>    Affects Versions: 1.0.0
>            Reporter: Olga Natkovich
>         Attachments: file_cmds-0305.patch, multi-store-0303.patch, 
> multi-store-0304.patch, multiquery-phase2_0313.patch, multiquery_0223.patch, 
> multiquery_0224.patch, multiquery_0306.patch
>
>
> Currently, if your Pig script contains multiple stores and some shared 
> computation, Pig will execute several independent queries. For instance:
> A = load 'data' as (a, b, c);
> B = filter A by a > 5;
> store B into 'output1';
> C = group B by b;
> store C into 'output2';
> This script will result in map-only job that generated output1 followed by a 
> map-reduce job that generated output2. As the resuld data is read, parsed and 
> filetered twice which is unnecessary and costly. 

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