Wait Event – read by other session

This event occurs when a session requests a buffer that is currently being read into the buffer cache by another session. Prior to release 10.1, waits for this event were grouped with the other reasons for waiting for buffers under the ‘buffer busy waits’ event. Wait Time: Time waited for the buffer to be read by the…

Wait Event – cursor: mutex X

The session requests the mutex for a cursor object in exclusive mode, and it must wait because the resource is busy. The mutex is busy because either the mutex is being held in exclusive mode by another session or the mutex is being held shared by one or more sessions. The existing mutex holder(s) must release…

Wait Event – cursor: mutex S

A session waits on this event when it is requesting a mutex in shared mode, when another session is currently holding a this mutex in exclusive mode on the same cursor object. Parameter Description P1 Hash value of cursor P2 Mutex value (top 2 bytes contain SID holding mutex in exclusive mode, and bottom two…

Wait Event – buffer read retry

This event occurs only if the instance is mounted in shared mode (Oracle Real Application Cluster). During the read of the buffer, the contents changed. This means that either: The version number, dba, or the incarnation and sequence number stored in the block no longer match The checksum on the block does not match the…