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https://issues.apache.org/jira/browse/PIG-627?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12676507#action_12676507
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Olga Natkovich commented on PIG-627:
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I committed the latest patch. Ran the unit tests and they all passed.
Couple of issues that need to be addressed:
(1) PigServer.openIterator, in batch mode, always returns an empty iterator.
That will not work if a script has a dump in it.
(2) PigSever.getStorePlan assumes that each alias maps to a single store. In
case of multiple queries that might not be true.
Thanks Richard and Gunther for your contribution!
> PERFORMANCE: multi-query optimization
> -------------------------------------
>
> Key: PIG-627
> URL: https://issues.apache.org/jira/browse/PIG-627
> Project: Pig
> Issue Type: Improvement
> Affects Versions: types_branch
> Reporter: Olga Natkovich
> Fix For: types_branch
>
> Attachments: multiquery_0223.patch, multiquery_0224.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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