[jira] [Assigned] (HIVE-8202) Support SMB Join for Hive on Spark [Spark Branch]

["Szehon Ho (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-8202?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Szehon Ho reassigned HIVE-8202:
-------------------------------

    Assignee: Szehon Ho  (was: Na Yang)

> Support SMB Join for Hive on Spark [Spark Branch]
> -------------------------------------------------
>
>                 Key: HIVE-8202
>                 URL: https://issues.apache.org/jira/browse/HIVE-8202
>             Project: Hive
>          Issue Type: Sub-task
>          Components: Spark
>            Reporter: Xuefu Zhang
>            Assignee: Szehon Ho
>
> SMB joins are used wherever the tables are sorted and bucketed. It's a reduce-side join. The join boils down to just merging the already sorted tables, allowing this operation to be faster than an ordinary map-join. However, if the tables are partitioned, there could be a slow down as each mapper would need to get a very small chunk of a partition which has a single key. Thus, in some scenarios it's beneficial to convert SMB join to SMB map join as well.
> The task is to research and support the conversion from regular SMB join to SMB map join for Spark execution engine.



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