Wait Event – cursor: pin X

A session waits on this event when it is requesting an exclusive mutex pin for a cursor object and it must wait because the resource is busy. The mutex pin for a cursor object can be busy either because a session is already holding it exclusive, or there are one or more sessions which are holding…

Wait Event – cursor: pin S wait on X

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

Wait Event – cursor: pin S

A session waits on this event when it wants to update a shared mutex pin and another session is currently in the process of updating a shared mutex pin for the same cursor object. This wait event should rarely be seen because a shared mutex pin update is very fast. Wait Time: Microseconds   Parameter Description P1…

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 – control file sequential read

Reading from the control file. This happens often. For example, while: Making a backup of the control files Sharing information (between instances) from the control file Reading other blocks from the control files Reading the header block Wait Time: The wait time is the elapsed time of the read   Parameter Description file# The control file from…

Wait Event – control file parallel write

This event occurs while the session is writing physical blocks to all control files. This happens when: The session starts a control file transaction (to ensure the control files are up to date in case the session crashes before committing the control file transaction) The session commits a transaction to a control file Changing a generic…

Wait Event – buffer deadlock

Oracle does not really wait on this event; the foreground only yields the CPU. Thus, the chances of catching this event are very low. This is not an application induced deadlock, but an assumed deadlock by the cache layer. The cache layer cannot get a buffer in a certain mode within a certain amount of…