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https://issues.apache.org/jira/browse/PIG-4495?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14484292#comment-14484292
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Daniel Dai commented on PIG-4495:
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+1
> Better multi-query planning in case of multiple edges
> -----------------------------------------------------
>
> Key: PIG-4495
> URL: https://issues.apache.org/jira/browse/PIG-4495
> Project: Pig
> Issue Type: Sub-task
> Components: tez
> Affects Versions: 0.14.0
> Reporter: Rohini Palaniswamy
> Assignee: Rohini Palaniswamy
> Fix For: 0.15.0
>
> Attachments: PIG-4495-1.patch, PIG-4495-2.patch
>
>
> Details in
> https://issues.apache.org/jira/browse/TEZ-1190?focusedCommentId=14393033&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14393033
> People split the data, perform some foreach transformations/filter, union
> them and then do some operation like group by or join with other data. In
> those cases it creates multiple edges from same Split, so we do not merge
> them, but
> write out the data to another dummy vertex to avoid multiple edges and this
> adds overhead and affects performance. Vertex groups accept multiple edges
> from same vertex. So if the multiple edges end up in a vertex group (and not
> a vertex which is the case in self join) we can avoid the dummy vertex.
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