[
https://issues.apache.org/jira/browse/MAPREDUCE-1176?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12794127#action_12794127
]
BitsOfInfo commented on MAPREDUCE-1176:
---------------------------------------
On second thought, I am thinking it might be better for this new
FixedLengthInputFormat config property to work as follows which gives greater
control over what can be used as the ByteWritable KEY value.
Permit the user to specify the start and end positions within a record which
define they key such as
FixedLengthInputFormat.defineKeyBoundaries(long start, long end)
> 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
>
>
> 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.
-
You can reply to this email to add a comment to the issue online.
