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From "Yi Tian (JIRA)" <>
Subject [jira] [Updated] (SPARK-6221) SparkSQL should support auto merging output files
Date Mon, 09 Mar 2015 06:48:38 GMT


Yi Tian updated SPARK-6221:
    Summary: SparkSQL should support auto merging output files  (was: SparkSQL should support
auto mergiing)

> SparkSQL should support auto merging output files
> -------------------------------------------------
>                 Key: SPARK-6221
>                 URL:
>             Project: Spark
>          Issue Type: New Feature
>          Components: SQL
>            Reporter: Yi Tian
> Hive has a feature that could automatically merge small files in HQL's output path. 
> This feature is quite useful for some cases that people use {{insert into}} to  handle
minute data from the input path to a daily table.
> In that case, if the SQL includes {{group by}} or {{join}} operation, we always set the
{{reduce number}} at least 200 to avoid the possible OOM in reduce side.
> That will cause this SQL output at least 200 files at the end of the execution. So the
daily table will finally contains more than 50000 files. 
> If we could provide the same feature in SparkSQL, it will extremely reduce hdfs operations
and spark tasks when we run other sql on this table.

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