weight of database calls?

On any platform you should be able to monitor the %age CPU used by each process( perfmon in windows) , the 'SQL' one say.if you run a test with 100 inserts , 100 selects , etc this can give you a rough guide to what is being used ( keep track of memory used as well).

One thing to be aware of is the complexity of database accesses. Should one use stored procedures / ( try the benchmarking i've outlined above). If its a simple lookup , maybe you dont need a full DB , more an ISAM access . As you said , inserts are expensive , so maybe you dont do them in real time , but send the INSERT stement to a message queue ( MSMQ or IBM MQ or the Java queuing system JMS) and then have a simple update program ( this could be on another machine) which does low priority processing of the updates.Big area this , also , make sure that you have enough machines doing this - Web/App/DB may not be enough.Good luck.

Actually INSERT is constant O(1)

Delete is constant O(1)

update is variable O(n)

fastest Select is O(LOGn)

For eg: $identify = $_post['identify']; $take care of = $_post['take care of']; $cellular = $_post['cellular']; $impression= mysql_query("insert into table_name (id,identify,take care of,cellular) values (' ', '$identify', '$take care of', '$cellular').mysql_error()"); if($impression) { echo "scriptalert('effectively inserted'); } else { echo "did not insert"; }