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Posted to dev@hive.apache.org by "Ashutosh Chauhan (JIRA)" <ji...@apache.org> on 2013/09/23 19:59:02 UTC
[jira] [Commented] (HIVE-5324) Extend record writer and ORC
reader/writer interfaces to provide statistics
[ 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:
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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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