So trying to push some inserts/updates to the background I added: async_workers=1 and replaced sql_xquery("ca", "$var(query)", "ra"); sql_result_free("ra"); with sql_query_async("ca", "$var(query)"); where: $var(query)="insert into CDR.callogs (accountcode,number) values ('"+$var(accountcode)+"',substring('"+$rU+"',1,4))"; Only to find out that the queries aren't inserted and the log contains: /usr/sbin/kamailio[24754]: ERROR: sqlops [sql_api.c:429]: sql_do_query_async(): the db driver module doesn't support async query The table is an InnoDB some insert delayed should give these kind of errors, but isn't the point of sql_query_async that it does the plain normal insert in a background task? Test machine: kamailio 4.2.5