DBMS_SERVER_ALERTS

Question

i found two ways to call set_threshold procedure of dbms_server_alerts
like one is
SQL> execute
2 dbms_server_alert.set_threshold(
3 dbms_server_alert.tablespace_pct_full,
4 dbms_server_alert.operator_ge, 90,
5 dbms_server_alert.operator_ge, 99,
6 1, 1, null,
7 dbms_server_alert.object_type_tablespace,'USERS2');
the null used above is instance name for RAC,,,if its not RAC the do we have to provide our instance name or will it take automatically the current instance name if no value is provided.
the other one is
EXEC DBMS_SERVER_ALERTS.SET_THRESHOLD(
METRICS_ID => CPU_TIME_PER_CALL,
WARNING_OPERATOR => OPERATOR_GT,
WARNING_VALUE => ‘15000’,
CRITICAL_OPERATOR => OPERATOR_GT,
CRITICAL_VALUE => ‘30000’, OBSERVATION_PERIOD => 10,
CONSECUTIVE_OCCURRENCES => 3);
is this just two different methods to call a procedure or they are for different purpose
well my other question is how do we found out the value for metrics_id like,,, now i only know two values that i can use in this parameter(CPU_TIME_PER_CALL and tablespace_pct_ful),,,what else i can use here ,,,,,is there any dictionary/dynamic view to find out what else values i can use here

Answer 1

Read the documentation...
DBMS_SERVER_ALERT
http://download.oracle.com/docs/cd/B19306_01/appdev.102/b14258/d_salt.htm#i1005585
Supported metrics:
http://download.oracle.com/docs/cd/B19306_01/appdev.102/b14258/d_salt.htm#i1007642