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https://issues.apache.org/jira/browse/PIG-4709?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15039710#comment-15039710
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liyunzhang_intel commented on PIG-4709:
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[~pallavi.rao]:
can you give an example to explain following in your review board? what is
algebraicOp.Final, algebraicOp.Intermediate,algebraicOp.Initial?
{code}
// Checks for algebraic operations and if they exist.
// Replaces global rearrange (cogroup) with reduceBy as follows:
// Input:
// foreach (using algebraicOp)
// -> packager
// -> globalRearrange
// -> localRearrange
// Output:
// foreach (using algebraicOp.Final)
// -> reduceBy (uses algebraicOp.Intermediate)
// -> foreach (using algebraicOp.Initial)
// -> localRearrange
{code}
> Improve performance of GROUPBY operator on Spark
> ------------------------------------------------
>
> Key: PIG-4709
> URL: https://issues.apache.org/jira/browse/PIG-4709
> Project: Pig
> Issue Type: Sub-task
> Components: spark
> Reporter: Pallavi Rao
> Assignee: Pallavi Rao
> Labels: spork
> Fix For: spark-branch
>
> Attachments: PIG-4709.patch
>
>
> Currently, the GROUPBY operator of PIG is mapped by Spark's CoGroup. When the
> grouped data is consumed by subsequent operations to perform algebraic
> operations, this is sub-optimal as there is lot of shuffle traffic.
> The Spark Plan must be optimized to use reduceBy, where possible, so that a
> combiner is used.
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