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https://issues.apache.org/jira/browse/SPARK-7637?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14543770#comment-14543770
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Rowan Chattaway edited comment on SPARK-7637 at 5/14/15 3:07 PM:
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I have made the changes and will submit a PR shortly.
was (Author: [email protected]):
I have made the changes and will submit a PR shortly. Can this jira be assigned
to me please?
> StructType.merge slow with large nenormalised tables O(N2)
> ----------------------------------------------------------
>
> Key: SPARK-7637
> URL: https://issues.apache.org/jira/browse/SPARK-7637
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 1.3.1
> Reporter: Rowan Chattaway
> Priority: Minor
> Original Estimate: 24h
> Remaining Estimate: 24h
>
> StructType.merge does a linear scan through the left schema and for each
> element scans the right schema. This results in a O(N2) algorithm.
> I have found this to be very slow when dealing with large denormalised
> parquet files.
> I would like to make a small change to this function to map the fields of
> both the left and right schemas resulting in O(N).
> This has a sizable increase in performance for large denormalised schemas.
> 10000x10000 column merge
> 2891ms Original
> 32ms with mapped field approach.
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