Where to count

I'm running a DB query on a database of firewall log entries (right now
around 700k rows). What I want to do is pull out some common entries, as
well as the number of times that they occur in the table.

Right now, I'm doing a query like:

select source,destination,service,count(*) FROM logs WHERE action='$type'
GROUP BY source,destination,service ORDER BY count DESC LIMIT $num;

This is a little more advanced than I'm used to doing, so I'm wondering if
that query is the best way to get that data, or if there's another way of
doing it.

Thanks,
Wade

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