[ http://issues.apache.org/jira/browse/HADOOP-450?page=comments#action_12427986 ] Doug Cutting commented on HADOOP-450: -------------------------------------
This issue is not about specifying multiple map functions per job. That should be a separate issue. This is just about moving the ownership of the key and value types from the job to the RecordReader. I don't understand your objections to the proposed new RecordReader methods createKey() and createValue(). The RecordReader is created by InputFormat.getRecordReader(), which is passed a JobConf, so the RecordReader has access to a JobConf when it creates key and value instances. The RecordReader can then use ReflectionUtils.newInstance() to create configured instances. > Remove the need for users to specify the types of the inputs > ------------------------------------------------------------ > > Key: HADOOP-450 > URL: http://issues.apache.org/jira/browse/HADOOP-450 > Project: Hadoop > Issue Type: Improvement > Components: mapred > Affects Versions: 0.5.0 > Reporter: Owen O'Malley > Assigned To: Owen O'Malley > Fix For: 0.6.0 > > > Currently, the application specifies the types of the input keys and values > and the RecordReader checks them for consistency. It would make more sense to > have the RecordReader define the types of keys that it will produce. > Therefore, I propose that we add two new methods to RecordReader: > WritableComparable createKey(); > Writable createValue(); > Note that I propose adding them to the RecordReader rather than the > InputFormat, so that they can specific to a particular input split. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
