[jira] [Resolved] (HIVE-2144) reduce workload generated by JDBCStatsPublisher

["Ning Zhang (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-2144?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ning Zhang resolved HIVE-2144.
------------------------------

       Resolution: Fixed
    Fix Version/s: 0.8.0
     Hadoop Flags: [Reviewed]

Committed. Thanks Tom!

Congrats on your 1st commit!

> reduce workload generated by JDBCStatsPublisher
> -----------------------------------------------
>
>                 Key: HIVE-2144
>                 URL: https://issues.apache.org/jira/browse/HIVE-2144
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: Ning Zhang
>            Assignee: Tomasz Nykiel
>             Fix For: 0.8.0
>
>         Attachments: HIVE-2144.1.patch, HIVE-2144.2.patch, HIVE-2144.patch
>
>
> In JDBCStatsPublisher, we first try a SELECT query to see if the specific ID was inserted by another task (mostly likely a speculative or previously failed task). Depending on if the ID is there, an INSERT or UPDATE query was issues. So there are basically 2x of queries per row inserted into the intermediate stats table. This workload could be reduced to 1/2 if we insert it anyway (it is very rare that IDs are duplicated) and use a different SQL query in the aggregation phase to dedup the ID (e.g., using group-by and max()). The benefits are that even though the aggregation query is more expensive, it is only run once per query. 

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