[ http://issues.apache.org/jira/browse/HADOOP-689?page=comments#action_12448829 ] Doug Cutting commented on HADOOP-689: -------------------------------------
Overall this looks good. A few issues. 1. A new array of classes should not be allocated for each call to readFields(). Perhaps instead introspection should be used to call a static getTypes() method and somehow cache this per subclass. At the least, the example code should create the array as a static field, and then have the getTypes() implementation return a reference to this. 2. set(), get(), and getTypes() need javadoc. > hadoop should provide a common way to wrap instances with different types > into one type > --------------------------------------------------------------------------------------- > > Key: HADOOP-689 > URL: http://issues.apache.org/jira/browse/HADOOP-689 > Project: Hadoop > Issue Type: Improvement > Components: io > Environment: All environment > Reporter: Feng Jiang > Attachments: HADOOP-689.patch > > > When two sequence files, which have same Key type but different Value types, > are mapped out to reduce, multiple Value types is not allowed. In this case, > we need a way to wrap instances with different types into one class type to > reduce. > In current code, ObjectWritable is a sole choice. but it costs too many > space, because the class declaration will be appended into output file as a > string for every Key-value pair. -- 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
