--group-by clause not working

[Fernando Ortega]

Hi, I'm using a standar Mysql 5.5 log (not Percona Server), and I'm
trying to work with percona toolkit.

So my slow-log is a normal Mysql 5.5 log.

Here you have an example of it:

# Time: 120425 13:47:40
# User@Host: vostro220[vostro220] @ [192.168.0.201]
# Query_time: 0.562500 Lock_time: 0.000000 Rows_sent: 15773
Rows_examined: 1340790
SET timestamp=1335354460;
SELECT p.idProducto, (....) FROM producto, (....) WHERE (....)

I've understood that I can only use Rows_sent or Rows_examined, buy
WHY I can't use --group-by tables option ? Does that option requerie
also a Mysql Percona server ?

pt-query-digest pcclonico-slow.log --filter '($event->{fingerprint}
=~ m/^(select)/)'

works perfectly, but

pt-query-digest pcclonico-slow.log --filter '($event->{fingerprint}
=~ m/^(select)/)' --group-by tables

doesn't work.

The onyl difference is the group-by clause. I think that percona-
toolkit get the table name from sql clause, but why it doesn't work ?

Could you make any test ?

Thanks a lot.