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From "Ashutosh Chauhan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-5324) Extend record writer and ORC reader/writer interfaces to provide statistics
Date Mon, 23 Sep 2013 17:59:02 GMT

    [ https://issues.apache.org/jira/browse/HIVE-5324?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13774784#comment-13774784
] 

Ashutosh Chauhan commented on HIVE-5324:
----------------------------------------

Few suggestions:
* Put StatsProvidingRecordWriter in o.a.h.ql.io package in its own file and provide javadoc
for it.
* For getRawDataSizeOfColumns(int[] colIndices); friendlier api is getRawDataSizeOfColumns(List<String>
colNames); Is that easy to do?
* Not sure if there is a usecase for these apis on writer. Is there any?
* Can you also add in code which invokes this new interface in this patch. (Not the impl of
interface). I guess that will be in FSOp::close()?
                
> Extend record writer and ORC reader/writer interfaces to provide statistics
> ---------------------------------------------------------------------------
>
>                 Key: HIVE-5324
>                 URL: https://issues.apache.org/jira/browse/HIVE-5324
>             Project: Hive
>          Issue Type: New Feature
>    Affects Versions: 0.13.0
>            Reporter: Prasanth J
>            Assignee: Prasanth J
>              Labels: orcfile, statistics
>             Fix For: 0.13.0
>
>         Attachments: HIVE-5324.1.patch.txt
>
>
> The current implementation for computing statistics (number of rows and raw data size)
happens for every single row processed. The processOp() method in FileSinkOperator gets raw
data size for each row from the serde and accumulates the size in hashmap while counting the
number of rows. This accumulated statistics is then published to metastore. 
> In case of ORC, ORC already stores enough statistics internally which can be made use
of when publishing the stats to metastore. This will avoid the duplication of work that is
happening in the processOp(). Also getting the statistics directly from ORC is very cheap
(can directly read from the file footer).

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