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Posted to user@hive.apache.org by Alex Boisvert <al...@bizo.com> on 2010/10/15 20:15:02 UTC

UDAF modes

Hi,

I'm writing a UDAF and I'm a little unclear about the PARTIAL1, PARTIAL2,
FINAL and COMPLETE modes.

I've read the extent of the Javadoc ;) and looked at some of the built-in
UDAFs in the Hive source tree and I'm still unclear about the properties of
the input data in each aggregation step.

Could anybody elaborate a little on the input data in each mode?  Say, what
are the safe assumptions for each mode assuming, e.g., CLUSTERED BY clause?

thanks!
alex