rlm_sql_log. accounting and locking

All, The rlm_sql_log module only logs a single query; unlike the main sql module which (for accounting) will do an update or insert if not found. How, if at all, are people merging the rows? Triggers? Post-processing? Also, I doubt it will be an issue, but just wanted to check; is the flock() of the file likely to cause any contention issues? Is there an easy way of hashing the NAS-IP-Address to writing to 26 files named "sql-log-[a-z]" and asking radsqlrelay to replay them all? Thoughts welcome. Regards, Phil