I'm unable to set the format of the outgoing date string in the constructor as it's supposed to work.
The only way i could change the format was to change the default in the java class and rebuild piggybank.
Apparently this has something to do with the way pig instantiates DateExtractor, quoting a replier on the mailing list:
David Vrensk said:
I ran into the same problem a couple of weeks ago, and
played around with the code inserting some print/log statements. It turns
out that the arguments are only used in the initial constructor calls, when
the pig process is starting, but once pig reaches the point where it would
use the udf, it creates new DateExtractors without passing the arguments.