hadoop-mapreduce-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "BitsOfInfo (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-1176) Contribution: FixedLengthInputFormat and FixedLengthRecordReader
Date Sat, 23 Mar 2013 22:01:14 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-1176?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13611876#comment-13611876
] 

BitsOfInfo commented on MAPREDUCE-1176:
---------------------------------------

I stopped working on it due to lack of time and mainly because of the tedium involved with
the back and forth over some minor points noted above. The code was functional, passed unit
tests and worked for my user case that triggered the work. 

I'd be happy to work with anyone who wants to take it over and get it moved forward into a
release.


                
> Contribution: FixedLengthInputFormat and FixedLengthRecordReader
> ----------------------------------------------------------------
>
>                 Key: MAPREDUCE-1176
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1176
>             Project: Hadoop Map/Reduce
>          Issue Type: New Feature
>    Affects Versions: 0.20.1, 0.20.2
>         Environment: Any
>            Reporter: BitsOfInfo
>            Priority: Minor
>         Attachments: MAPREDUCE-1176-v1.patch, MAPREDUCE-1176-v2.patch, MAPREDUCE-1176-v3.patch,
MAPREDUCE-1176-v4.patch
>
>
> Hello,
> I would like to contribute the following two classes for incorporation into the mapreduce.lib.input
package. These two classes can be used when you need to read data from files containing fixed
length (fixed width) records. Such files have no CR/LF (or any combination thereof), no delimiters
etc, but each record is a fixed length, and extra data is padded with spaces. The data is
one gigantic line within a file.
> Provided are two classes first is the FixedLengthInputFormat and its corresponding FixedLengthRecordReader.
When creating a job that specifies this input format, the job must have the "mapreduce.input.fixedlengthinputformat.record.length"
property set as follows
> myJobConf.setInt("mapreduce.input.fixedlengthinputformat.record.length",[myFixedRecordLength]);
> OR
> myJobConf.setInt(FixedLengthInputFormat.FIXED_RECORD_LENGTH, [myFixedRecordLength]);
> This input format overrides computeSplitSize() in order to ensure that InputSplits do
not contain any partial records since with fixed records there is no way to determine where
a record begins if that were to occur. Each InputSplit passed to the FixedLengthRecordReader
will start at the beginning of a record, and the last byte in the InputSplit will be the last
byte of a record. The override of computeSplitSize() delegates to FileInputFormat's compute
method, and then adjusts the returned split size by doing the following: (Math.floor(fileInputFormatsComputedSplitSize
/ fixedRecordLength) * fixedRecordLength)
> This suite of fixed length input format classes, does not support compressed files. 

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira

Mime
View raw message