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Date: Tue, 28 Oct 2014 02:23:33 +0000 (UTC)
From: "Szehon Ho (JIRA)" <jira@apache.org>
To: hive-dev@hadoop.apache.org
Message-ID: <JIRA.12742899.1411173331000.350247.1414463013852@Atlassian.JIRA>
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Subject: [jira] [Updated] (HIVE-8202) Support SMB Join for Hive on Spark
 [Spark Branch]
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     [ https://issues.apache.org/jira/browse/HIVE-8202?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Szehon Ho updated HIVE-8202:
----------------------------
    Attachment: HIVE-8202.3-spark.patch

> 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
>         Attachments: HIVE-8202.1-spark.patch, HIVE-8202.2-spark.patch, HIVE-8202.3-spark.patch, Hive on Spark SMB Join.docx, Hive on Spark SMB Join.pdf
>
>
> 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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