Even in SQL when you do select count(*) you are actually grouping, the language just hides it from you.
Each map/combiner counts the number of records it sees and sends that count to the reducer which sums the counts. Alan. On Aug 29, 2012, at 4:41 PM, Mohit Anchlia wrote: > Thanks! Why is grouping necessary? Is it to send it to the reducer? > > On Wed, Aug 29, 2012 at 4:03 PM, Alan Gates <[email protected]> wrote: > >> A = load 'foo'; >> B = group A all; >> C = foreach B generate COUNT(A); >> >> Alan. >> On Aug 29, 2012, at 3:51 PM, Mohit Anchlia wrote: >> >>> How do I get count of all the rows? All the examples of COUNT use group >> by. >> >>
