killing sessions and OS processes

been dealing with hung sessions today.
I'm still not sure of why are they being left there hanging. They are just ready to wait eternally for the "SQL*Net message from dblink" event. I guess that remote instance is failing or something.. I don't have access to that server, so I don't know what's happening there and admins are finns - pretty quiet types, they don't talk much. Anyway. I have faced a problem of having a big number of sessions either waiting for dblink or for client message and I KNOW that neither is coming. So a need in mass killing appears :) You can kill oracle sessions with

ALTER SYSTEM KILL SESSION SID, SERIAL# immediate;

But after you kill it like this, it still stays in the v$session view having the 'KILLED' status. And you cannot get rid of it otherwise but killing the process on the OS level. Because PMON waits for a client to issue next command so to send him "your session has been killed" message, before he can actually eliminate the process. Quite polite, but sometimes you just know that client is not coming back... For this matter there is a orakill.exe tool (for Windows). Used like this:

orakill [instance_name] [spid]

This one will kill the thread inside the oracle.exe process. You need to pass the spid of the process, taken from the v$process view.

So there were two problems in front of me:

1. To kill all the sessions started by a specific program.
2. To kill the processes so that all the resources and locks would be freed.

To solve the first one I coded a nice PL/SQL procedure:

CREATE OR REPLACE PROCEDURE KILL_SESSIONS_BY_PROGRAM (in_program IN varchar2) IS
CURSOR sessions_cur IS
select s.sid
,s.serial#
from v$session s
where lower(s.program)=lower(in_program)
and s.status != 'KILLED';
sessions_rec sessions_cur%ROWTYPE;
sess_to_kill varchar2(50);
cmd_string varchar2(100);
e_marked_for_kill exception;
PRAGMA EXCEPTION_INIT(e_marked_for_kill, -31);
begin
OPEN sessions_cur;
LOOP
FETCH sessions_cur INTO sessions_rec;
IF sessions_cur%ROWCOUNT = 0 AND sessions_cur%NOTFOUND THEN
RAISE_APPLICATION_ERROR (-20001,'NO sessions found!');
END IF;
EXIT WHEN sessions_cur%NOTFOUND;
sess_to_kill := TO_CHAR(sessions_rec.sid)','TO_CHAR(sessions_rec.serial#);
cmd_string:='ALTER SYSTEM KILL SESSION '''sess_to_kill''' immediate';
begin
DBMS_OUTPUT.PUT_LINE(cmd_string);
execute immediate cmd_string;
exception when e_marked_for_kill then
null;
end;
END LOOP;
end;
/

And for the second one I made a small SQLPlus script, which generates me a .cmd file containg as much orakill commands as it is needed. Here it is:

CLEAR BUFFER
set heading off;
set feedback off;
variable sess refcursor;
begin
open :sess for select 'orakill &instance ' p.spid
from v$session s, v$process p
where s.paddr = p.addr
and lower(s.program)=lower('&in_program')
and s.status = 'KILLED';
end;
/
spool h:\sql\kill.cmd;
print sess;
spool off;

privileges in bulk

have been dealing with oracle privileges today for the first time seiously.

It turned out that granting privileges is quite a pain (as everything else) in oracle. I needed to grant select (or any other) privilege on all tables in a schema at once. But oracle standard command only makes it possible to grant privs on a single object. So I had to write my own procedure, which would grant privileges in bulk. Here it is:

CREATE OR REPLACE PROCEDURE GRANT_BULK_PRIV (inSchema IN varchar,
inObjType IN varchar,
inPriv IN varchar,
inUser IN varchar) IS
/******************************************************************************
NAME: GRANT_MULTI_PRIV
PURPOSE: to grant priviledges in bulk
NOTES:
PARAMETERS:
inObjType must specify the oracle defined type of the object (in upper case)
inSchema: Name of the schema where the objects reside (must be in upper case)
inPriv: what priviledge to give (oracle defined privilege name)
inUser: a user or a role to whom the privilege will be granted
Sysdate: 8.02.2007
******************************************************************************/
cursor allobjects (inOwner IN varchar, inType IN varchar) IS
Select o.object_name, o.status
from sys.all_objects o
where o.object_type = inType
and o.owner = inOwner
and o.status = 'VALID' ;
allobjects_rec allobjects%rowtype;
cmdtext varchar(255);
BEGIN
OPEN allobjects (inSchema, inObjType);
LOOP
FETCH allobjects INTO allobjects_rec;
EXIT WHEN allobjects%NOTFOUND;
cmdtext:= 'grant ' ||inPriv|| ' on ' ||inSchema|| '."' || allobjects_rec.object_name ||'" to '|| inUser;
--DBMS_OUTPUT.PUT_LINE(cmdtext);
execute immediate cmdtext;
END LOOP;
EXCEPTION
WHEN NO_DATA_FOUND THEN
NULL;
WHEN OTHERS THEN
-- Consider logging the error and then re-raise
RAISE;
END GRANT_BULK_PRIV;
/

usage like this:
execute grant_bulk_priv ('SHEMA', 'TABLE', 'SELECT', 'SOME_ROLE');