Slow response when query v$lock or some data dictionary

Question

Hello,
We have a severe problem with our database performance problem. Here is the situation:
1. When query data dictionary such as v$lock from any Windows machine on the network, the performance is slow (about 3 minutes.)
2. When query v$lock directly on the server where database reside, the query come back fast (normal).
3. When query user table such as employees from any windows machine on the network, the performance is normal.
4. When query user table directly from server where the database reside, the query come back normal.
Looking at v$session_wait on the slow query, it is waiting on "SQL*Net message to client".
We have people from our network group, security group and did not find anything problem.
Thank for you help!!!

Answer 1

user8175606 wrote:
Hello,
We have a severe problem with our database performance problem. Here is the situation:
1. When query data dictionary such as v$lock from any Windows machine on the network, the performance is slow (about 3 minutes.)
2. When query v$lock directly on the server where database reside, the query come back fast (normal).
3. When query user table such as employees from any windows machine on the network, the performance is normal.
4. When query user table directly from server where the database reside, the query come back normal.
Looking at v$session_wait on the slow query, it is waiting on "SQL*Net message to client".
We have people from our network group, security group and did not find anything problem.
Thank for you help!!!I saw the same problem several times. All of them were related with wrong execution plan in the v$lock (and dba_locks, and others based on v$lock). For instance due to "crazy" optimizer mode FIRST_ROWS.
Also look at note 431770.1.
I suggest that when you looked at v$session_wait and saw the event "SQL*Net message to client" state of the event was not = WAITING. Please check. It means that Oracle is not waiting but is burning CPU.
Thus, please let us know - does another optimizer mode improve performance?
select /*+ all_rows */ * from v$lock;
select /*+ rule */ * from v$lock;