Retrieve alert values for use as parameter in corrective action sql script

Question

I am trying to write a corrective action sql script to kill a session that is blocking other sessions. I have the "blocking session count" metric set and the alert is firing correctly.
Is there any way to retrieve the sid and serial number from the alert generated and use it in a corrective action sql script?
Here is the alert generated:
Target Name=myproddb.world
Target Type=Database Instance
Host=myprodserver
Metric=Blocking Session Count
Blocking Session ID=SID: 522 Serial#: 5228
Timestamp=Mar 4, 2008 5:57:12 PM EST
Severity=Warning
Message=Session 522 is blocking 1 other sessions
Notification Rule Name=Testing Corrective actions
Notification Rule Owner=sysman
Clearly the sid, and serial # is contained within the alert Message field
what I want to write for the sql script is :
alter system kill session '%sid%,%serial_no%' immediate;
and have GC pass in the sid and serial_no to the script.
The "Target Properties" listed on the right of the Edit Corrective Action screen lists minimal details pertaining to the alert and certainly not the session sid, serial no.
Generically, is there any way to retrieve the values from an alert and use them in a corrective action script or job?
I've looked into getting the values from the mgmt$alert_history table, but I'm hoping that GC can pass the values to the sql script.
thanks in advance for your help.

Answer 1

Hi
You can implementing a procedure like this.
1. When a block session count alarms occurs, there is a column in the v$lock that you can examine.
#!/bin/ksh
#kill_block_session.sh
#first export your variables
export ORACLE_HOME=/oracle/product/10.2.0.3
export ORACLE_SID=SIDNAME
$ORACLE_HOME/bin/sqlplus "/ as sysdba" << EOF
execute immediate killed_blocks;
EOF
# end
The killed_blocks is a procedure:
create procedure
declare
v_sid varchar2(15);
v_serial varchar2(15);
-- now a sql query that retrieve the sid and serial
-- you can obtain these values from v$session and v$lock
select vs.sid,vs.serial into v_sid,v_serial
from v$session vs,v$lock vl
where vs.sid=vl.sid
and vl.block >0
-- After this, you execute a dbms_put line with these
-- values
But you understant that this response action is very dangerous, because its possible that you kill sessions that the blocking are transitient.
You must examine your enviroment and your application and establish the metric like UDM and not for only session blocking count.
You must to see:
- The type of block
- The ctime time in the v$lock for to understatn the amount of time to determine that the block is need killed.
- In my opinion you need a special UDM and deactivate the blocking sesion count
If you want help to create this UDM send me a mail to [email protected]
Regards
Robert