Null Event waiting in V$session_wait
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  1. #1
    Join Date
    Apr 2001
    Location
    Ludhiana (Punjab) India
    Posts
    36

    Null Event waiting in V$session_wait

    Hello friends,

    I have HP prolient ML350 server having 2 cpu (3 ghz xenon) & 3 gb ram running windows 2000 server. I have oracle 9.2.0.1.0. I am getting a problem when ever i connect as (system) user from client machine in v$session_wait view it shows that user as NULL EVENT & having following output .


    SID EVENT P1 P2 P3 WAIT_TIME SECONDS_IN_WAIT
    ---- ------- --- --- --- ------------- --------------------
    28 null 675562835 1 0 -1 0 waited unknown
    event time

    i have installed oracle on another test server also and there it also giving the same thing. can any one tell why it is


    Sethi

  2. #2
    Join Date
    Feb 2003
    Posts
    63

    Which Version?

    Which Version of Oracle are you currently running?

  3. #3
    Join Date
    Apr 2001
    Location
    Ludhiana (Punjab) India
    Posts
    36

    Reply

    Hi

    I am running 9i release 2 (9.2.0.1.0).

    Thanks

    Gurpreet Sethi

  4. #4
    Join Date
    Nov 2005
    Posts
    32
    There have been instances of 9i version of oracle masking the actual wait events with the "null event". You can maybe enable event 10046 for the session that's experiecing the "null event" and see if the event can trace the actual wait events that might be occuring. To enable event 10046 for a different session, you can use the dbms_system.set_ev procedure:

    SQL> exec dbms_system.set_ev(sid,serial#,EV=>10046,LE=>12,NM=>'')

    Good luck!

    http://www.dbaxchange.com

  5. #5
    Join Date
    May 2000
    Location
    ATLANTA, GA, USA
    Posts
    3,135
    Actually "NULL EVENT" can be found in v$event_name in 9i.
    See below:
    SQL> L
    1 select name from v$event_name
    2* where name = 'null event'
    SQL> /

    NAME
    ----------------------
    null event

    My guess is:
    Since there are 800 events in 10g and 400 in 9i, the kernel developers of ORACLE suggested to add this in 9i, so that their code can be easily modified later in 10g to accomodate more specific events.

    Tamil

  6. #6
    Join Date
    Nov 2005
    Posts
    32
    Tamilselvan,

    Yes, "null event" is a valid idle wait event that can potentially occur when a piece of code (explicit or implicit) calls the wait interface without an event id. However, for 9i version of oracle, there is a known bug that has been fixed in 9.2.0.4 where oracle has replaced "null event" with "unspecified event" to indicate a wait state
    where no named event has been supplied.
    The individual who has posted below has the problem with the "null event" wait event in 9.2.0.1 and that's one of the versions of 9i being affected.

    Thanks!

    http://www.dbaxchange.com

  7. #7
    Join Date
    Feb 2003
    Posts
    63

    Bug

    I read somewhere on metalink about this being a bug with 9.2.0.1 it suggests upgrading as it is resolved in 9.2.0.3
    HTH

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