Hi Dhaval, What do you mean by "a custom group function"? To create a function that turns a tuple or a part of a tuple into a key you want to group by, you can use a regular EvalFunc. To create a custom aggregation function that performs some calculation on the result of grouping, you still write a regular EvalFunc, except it must work on a bag. You can implement the Algebraic interface to make it run faster: http://hadoop.apache.org/pig/docs/r0.5.0/udf.html .
If you are working with the version in trunk, there is another interface you can implement for further efficiency gains, if it is applicable to your use case: http://wiki.apache.org/pig/PigAccumulatorSpec <http://wiki.apache.org/pig/PigAccumulatorSpec>-Dmitriy On Tue, Nov 24, 2009 at 3:56 AM, dhaval deshpande < [email protected]> wrote: > Hi, > i wanted to create a custom group function in pig. I was not sure > where to start from. I check some documentation online but couldnt figure > out. I also checked on wiki and it says I need to extend a abstract class > GroupFunc. and when i try to do that it says GroupFunc class doesnt not > exist. Please help me where do I start from. > > Thanks, > Dhaval. >
