hadoop-common-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Mahadev konar (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-4065) support for reading binary data from flat files
Date Mon, 08 Sep 2008 21:33:44 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-4065?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12629298#action_12629298
] 

Mahadev konar commented on HADOOP-4065:
---------------------------------------

we at yahoo have been working on similar kind of files where data is just stored as binary
data and is splittable. 

http://issues.apache.org/jira/browse/HADOOP-3315

the  spec is old and needs to be updated. TFile is meant to be a sequence file replacement.


  A TFile is a container of key-value pairs. Both keys and values are type-less
  byte arrays. Keys can be up to 64KB, value length is not restricted. TFile
  further provides the following features:
- Block Compression.
- Named meta data blocks.
- Sorted or unsorted keys.
- Seek by key or by file offset.

We will update the specs on HADOOP-3315 by the end of this week. 



> support for reading binary data from flat files
> -----------------------------------------------
>
>                 Key: HADOOP-4065
>                 URL: https://issues.apache.org/jira/browse/HADOOP-4065
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: mapred
>            Reporter: Joydeep Sen Sarma
>
> like textinputformat - looking for a concrete implementation to read binary records from
a flat file (that may be compressed).
> it's assumed that hadoop can't split such a file. so the inputformat can set splittable
to false.
> tricky aspects are:
> - how to know what class the file contains (has to be in a configuration somewhere).
> - how to determine EOF (would be nice if hadoop can determine EOF and not have the deserializer
throw an exception  (which is hard to distinguish from a exception due to corruptions?)).
this is easy for non-compressed streams - for compressed streams - DecompressorStream has
a useful looking getAvailable() call - except the class is marked package private.

-- 
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