Algorithm::Accounting provide simple aggregation method to make log 
accounting easier. It accepts data in rows, each rows can have many 
fields, and each field is a scalar or a list(arrayref).

The basic usage is you walk through all your logs, and use append_data() 
to insert each rows, (you'll have to split the line into fields), and 
then call result() to retrieve the result, or report() to immediately 
see simple result.

You may specify a filed_groups parameter (arrayref of arrayref), and 
Algorithm::Accounting will account these fields in groups.

WWW: http://search.cpan.org/dist/Algorithm-Accounting/