hive-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Thejas M Nair (JIRA)" <>
Subject [jira] [Updated] (HIVE-7659) Spark: Unnecessary sort in query plan
Date Thu, 14 Aug 2014 12:25:13 GMT


Thejas M Nair updated HIVE-7659:

    Summary: Spark: Unnecessary sort in query plan  (was: Unnecessary sort in query plan)

> Spark: Unnecessary sort in query plan
> -------------------------------------
>                 Key: HIVE-7659
>                 URL:
>             Project: Hive
>          Issue Type: Improvement
>          Components: Spark
>            Reporter: Rui Li
>            Assignee: Rui Li
>         Attachments: HIVE-7659-spark.patch
> For hive on spark.
> Currently we rely on the sort order in RS to decide whether we need a sortByKey transformation.
However a simple group by query will also have the sort order set to '+'.
> Consider the query: select key from table group by key. The RS in the map work will have
sort order set to '+', thus requiring a sortByKey shuffle.
> To avoid the unnecessary sort, we should either use another way to decide if there has
to be a sort shuffle, or we should set the sort order only when sort is really needed.

This message was sent by Atlassian JIRA

View raw message