[SR-Users] MYSQL and various

Dear list, on my kamailio 4.4.7 i use interactions with MYSQL. For example .. i use it for some black list control and other like this..         sql_query("cb", "select id from blacklist where cli='$var(g2)' and (ippeer = '$si' or ippeer = 'ALL')", "rabl");         if($dbr(rabl=>rows)>0){                 sql_result_free("rabl");                 sl_send_reply("403","Forbidden blacklist");                 exit;         }         sql_result_free("rabl"); I was wonder what was the best method to prevent the query going on if mysql don't respond for high load or other situation.. If Mysql is not able to reply to the query tight now the call continue over the configuration... what is the best way to prevent this and for examples drop it with  a standard SIP 503 error. I have search on docs.. but i haven't found any valid way. Thanks Laura