hadoop-mapreduce-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Owen O'Malley (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAPREDUCE-606) Implement a binary input/output format for Streaming
Date Tue, 08 Dec 2009 18:17:18 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-606?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12787620#action_12787620
] 

Owen O'Malley commented on MAPREDUCE-606:
-----------------------------------------

I'd propose that we implement this in terms of the org.apache.hadoop.streaming.io.InputWriter
and OutputReader. A reader/writer that left the bytes alone, but that quoted the other characters
would be great:

{noformat}
newline -> \n
return -> \r
backslash -> \\
tab -> \t
{noformat}

Then it would be easy to get quoted binary into streaming applications.

> Implement a binary input/output format for Streaming
> ----------------------------------------------------
>
>                 Key: MAPREDUCE-606
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-606
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: contrib/streaming
>            Reporter: Arun C Murthy
>         Attachments: hadoop-3227.patch
>
>
> Lots of streaming applications process textual data with 1 record per line and fields
separated by a delimiter. It turns out that there is no point in using any of Hadoop's input/output
formats since the streaming script/binary itself will parse the input and break into records
and fields. In such cases we should provide users with a binary input/output format which
just sends 64k (or so) blocks of data directly from HDFS to the streaming application.
> I did something very similar for Pig-Streaming (PIG-94 - BinaryStorage) which resulted
in 300%+ speedup for scanning (identity mapper & map-only jobs) data... the parsing done
by input/output formats in these cases were pure-overhead.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


Mime
View raw message