Null Event is not an empty event, not waiting for an event, but Oracle forgot what the name of the event just waiting is, but retains the true situation of the event. Oracle's developers updated these event names until 9.2.0.3. Is that all we have to Patch to 9.2.0.3 whenever we encounter performance issues? We already know that his real situation is still embodied in the P1, P2, P3 parameters of V $ session_wait, so we can touch the vines from these parameters, find out what this null evenet is waiting for the event. Here is some information about COPY on ITPub: 1. Lck Processes to Pick Up extra or mussed 'posts' (Messages) .IN All Cases That Can Be Identified The Wait Time Is Zero, Althuary On Most Ports this is Changed to 1 / 100th second inorder to force the process to be rescheduled.2 Multiple DB writers.Two cases: -. When the master has sent i / o requests to the slaves, itwaits on this event for up to 6 seconds until the slavessignal that the i / O is Complete.- The Slaves Wait on this Event for Up 3 Seconds Whilstwaiting for Requests from The master DB Writer. There are also SQL * Net Message to Client, DB File, which has been confirmed to NULL EVENT. Scattered (or Sequential) Read is for =========================== Test on your machine: [Code] SQL> SELECT SID, EVENT , P1, P2, P3 from V $ session_wait;
SID EVENT P1 P2 P3 ---------- --------------------------------- -------------- ---------- 11 Null Event 2056367224 155 0 12 Null Event 1111838976 1 0 1 PMON Timer 300 0 0 2 RDBMS IPC Message 300 0 0 3 RDBMS IPC Message 300 0 0 6 RDBMS IPC Message 180000 0 0 7 RDBMS IPC Message 300 0 0 4 RDBMS IPC Message 300 0 0 5 SMON TIMER 300 0 0 9 SQL * Net Message from Client 1111838976 1 0 8 Wakeup Time Manager 0 0 0 011 rows selected. [/ Code] SID is 12 of NULL EVENT wait The same is the same as the SID 9 - "SQL * Net Message from Client" =============================== =============
