Thanks. Dev
On Wed, Jul 29, 2009 at 2:27 AM, Todd Lipcon <[email protected]> wrote: > On Tue, Jul 28, 2009 at 11:24 AM, Devajyoti Sarkar <[email protected]> > wrote: > > > Hi, > > > > In the hadoop documentation it says that all key-value classes need to > > implement Writable to allow serialization and de-serialization of outputs > > between mappers and reducers. Is this also necessary for key/value pairs > > sent between the RecordReader and the Mapper (as well as the Reducer and > > the > > RecordWriter)? I assume that each of these two cases, classes are > > instantiated in the same VM. So is it safe to assume that key/value pairs > > are sent by reference instead of serialization/deserialization? If so, my > > specific application may get a performance boost. Please do let me know > if > > this so. > > > > Yes, this is correct. The values that come out of RecordReaders and go into > RecordWriters do not need to implement Writable. > > -Todd >
