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Mariappan Asokan updated MAPREDUCE-1176: ---------------------------------------- Affects Version/s: (was: 2.0.5-alpha) (was: 2.1.0-beta) 2.2.0 Status: In Progress (was: Patch Available) > 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: 2.2.0 > Environment: Any > Reporter: BitsOfInfo > Assignee: Mariappan Asokan > Attachments: MAPREDUCE-1176-v1.patch, MAPREDUCE-1176-v2.patch, > MAPREDUCE-1176-v3.patch, MAPREDUCE-1176-v4.patch, 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 was sent by Atlassian JIRA (v6.1#6144)