Database hangs during import

Question

hi guys,
one of our client using oracle 9i R2 on windows server 2003 platform.
they used to make export backup.when they called me and show me that when they import a schema, import hangs at one large table (i think containing more that 4000,000 rows).
i couldn't understand what might be the problem.it is also not generating any kind of error.
where should i look for tuning???
thanks and regards
VD

Answer 1

As Sybrand suggested you have to check some of the V$ views.
You need to understand what your session is waiting for.
In order to do that you have to find the session ID of the import process. You can use V$SESSION view Link to the 9iR2 Reference Page
In order to get to the right session id use USERNAME='<i>user performing the import</i>' and STATUS='ACTIVE'.
Once you have the right SESSION ID, you can query V$SESSION_WAIT and V$SESSION_EVENT.
- V$SESSION_WAIT will give you the information what the session is currently waiting on. Link to the 9iR2 Reference Page
- V$SESSION_EVENT will give you the information about the wait events this session was waiting so far. Link to the 9iR2 Reference Page
And that is all you need to get the initial clue on what is going on.
Additionally, you may want to query V$SQLAREA to get the current SQL your session is executing.
Link to the 9iR2 Reference Page
Moreover, if you need to get even more details, you may want to turn SQL tracing on (event 10046).
The queries below are just examples on how you can use the views from above to get the information you need:
select      s.sid
       , s.username
       , sw.event
         , sw.P1TEXT
         , sw.P1
       , sw.P2TEXT
          , sw.P2
from
        v$session s
        , v$session_wait sw
where s.sid=sw.sid
  and s.status='ACTIVE'
  and s.username=&my_username
  and s.username is not nullThe query above will give you information about what the current active sessions are waiting for.
The query below will give you information about all of the wait events a particular session was waiting so far.
select sid
     , event
     , total_waits
     , time_waited
     , average_wait
     , max_wait
from v$session_event
where sid=&my_sid
order by time_waited descBut the information provided by the views and queries above are not going to be useful if you don't understand how to interpret it.
Again, read the documentation, forums, blogs to learn more on how to use Oracle Wait Interface to make your debugging/optimization easier.
vikrant dixit wrote:
and by posting here we minimize the searching time,experimentation time, etc. dont u think so?That might be true, but the benefit you are going to gain would be a temporary one. The next time you run into the same problem, you will post the question again and again and again ... You must agree that sometimes you might not get the answers right away..
Cheers,