[jira] [Assigned] (HIVE-74) Hive can use CombineFileInputFormat for when the input are many small files

["Rajesh Balamohan (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-74?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Rajesh Balamohan reassigned HIVE-74:
------------------------------------

    Assignee: Rajesh Balamohan  (was: Namit Jain)

> Hive can use CombineFileInputFormat for when the input are many small files
> ---------------------------------------------------------------------------
>
>                 Key: HIVE-74
>                 URL: https://issues.apache.org/jira/browse/HIVE-74
>             Project: Hive
>          Issue Type: Improvement
>          Components: Query Processor
>            Reporter: dhruba borthakur
>            Assignee: Rajesh Balamohan
>             Fix For: 0.5.0
>
>         Attachments: hive.74.1.patch, hive.74.2.patch, hiveCombineSplit.patch, hiveCombineSplit.patch, hiveCombineSplit2.patch
>
>
> There are cases when the input to a Hive job are thousands of small files. In this case, there is a mapper for each file. Most of the overhead for spawning all these mappers can be avoided if Hive used CombineFileInputFormat introduced via HADOOP-4565
> Options to control this behavior:
> {code}
> hive.input.format (org.apache.hadoop.hive.ql.io.CombineHiveInputFormat (default, if empty), or org.apache.hadoop.hive.ql.io.HiveInputFormat)
> mapred.min.split.size.per.node (the minimum bytes of data to create a node-local partition, otherwise the data will combine to rack level. default:0)
> mapred.min.split.size.per.rack (the minimum bytes of data to create a rack-local partition, otherwise the data will combine to global level. default:0)
> mapred.max.split.size (the max size of each split, will be exceeded because we stop accumulating *after* reaching it, instead of before)
> {code}
> The 3 numbers above must be in non-descending order.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)