Wait Event

Performance views which is related to the wait event is as follows.

• v$system_event V$SYSTEM_EVENT

• v$session_event V$SESSION_EVENT

• v$session_wait V$SESSION_WAIT

• v$wait_event_name V$WAIT_EVENT_NAME

• v$wait_event_class_name V$WAIT_EVENT_CLASS_NAME

Class of Wait Event

• Administrative: Waits resulting from DBA commands that cause users to wait (for example, an index rebuild)

• Application: Waits resulting from user application code (for example, lock waits caused by row level locking or explicit lock commands)

• Cluster: Waits related to cluster resources (for example, global cache resources )

• Commit: This wait class only comprises one wait event - wait for redo log write confirmation after a commit (that is, 'log file sync')

• Concurrency: Waits for internal database resources (for example, latches)

• Configuration: Waits caused by inadequate configuration of database or instance resources (for example, undersized log file sizes, shared pool size)

• Idle: Waits that signify the session is inactive, waiting for work (for example, 'gsql message from client')

• Network: Waits related to network messaging

• Other: Waits which should not typically occur on a system

• Scheduler: Resource manager related waits

• System IO: Waits for background process IO

• User IO: Waits for user IO

Item of Wait Event

ENQUEUE: GDISPATCHER REQUEST

It is the time a request waits in the queue when GDISPATCHER sends it to the shared server.
Parameter: None

ENQUEUE: SHARED-SERVER RESPONSE

It is the time a response waits in the queue when the shared server sends it to GDISPATCHER.
Parameter: None

DEQUEUE: SHARED-SERVER REQUEST

It is the time a request waits in the queue when the shared server receives it from GDISPATCHER.
Parameter: None

DEQUEUE: GDISPATCHER RESPONSE

It is the time a response waits in the queue when GDISPATCHER receives it from the shared server.
Parameter: None

SEND: DEDICATE-SERVER SPOOLED RESPONSE

It is the time a dedicated server waits in the socket or IPC when sending a spooled response to the client.

SEND: DEDICATE-SERVER RESPONSE

It is the time a dedicated server waits in the socket or IPC when sending a response to the client.

RECV: DEDICATE-SERVER REQUEST

It is the time a dedicated server waits in the socket or IPC when receiving a request from the client.
Parameter: None

SEND: GDISPATCHER RESPONSE

It is the time GDISPATCHER waits in the socket when sending a response to the client.

RECV: GDISPATCHER REQUEST

It is the time GDISPATCHER waits in the socket when receiving a request from the client.
Parameter: None

ENQUEUE: CLUSTER REQUEST

It is the time a request waits in the queue when sent remotely in a cluster.
Parameter: None

ENQUEUE: CLUSTER BROADCAST REQUEST

It is the time a broadcast request waits in the queue when sent remotely in a cluster.
Parameter: None

DEQUEUE: CLUSTER RESPONSE

It is the time a response waits in the queue when received remotely in a cluster.
Parameter: None

SEND: CDISPATCHER

It is the time CDISPATCHER waits in the socket when sending a message remotely.
Parameter: None

RECV: CDISPATCHER

It is the time CDISPATCHER waits in the socket when receiving a message remotely.
Parameter: None

WAIT TRANSACTION

It is the time spent waiting for a specific transaction to complete.

WAIT OTHER TRANSACTION

It is the time spent waiting while another transaction holds a lock. 
For example, if transaction A is waiting for the completion of transaction B, it refers to the waiting time of A.

WAIT ENABLE LOGGING

It is the time spent waiting until logging is allowed.
Parameter: None

WAIT LOG FLUSHER

It is the time the session waits until the log flusher writes the log to the disk.

WAIT XA CONTEXT

It is the time the session waits when the XA context is being used by another session.
Parameter: None

LATCH: LOG BUFFER

It is the time spent waiting to acquire the latch for the log buffer.

LATCH: PROCESS MANAGER

It is the time spent waiting to acquire the latch for the process manager.

LATCH: ENV MGR

It is the time spent waiting to acquire the latch for the env manager.

LATCH: SESSION ENV MGR

It is the time spent waiting to acquire the latch for the session env manager.

LATCH: PCH

It is the time spent waiting to acquire the latch for the Page Control Header (PCH).

LATCH: PAGE

It is the time spent waiting to acquire the latch for the page layer.

LATCH: PENDING LOG

It is the time spent waiting to write a log to the pending log buffer.

LATCH: ALLOC TRANS

It is the time spent waiting to allocate a transaction slot.

LATCH: UNDO SEGMENT

It is the time spent waiting to acquire the latch for the undo segment.

LATCH: CLUSTER LOCATION

It is the time spent waiting to acquire the latch for the cluster location.

LATCH: DICT HASH ELEMENT AGING

It is the time spent waiting in the latch while aging a deleted dictionary cache.

LATCH: DICT HASH RELATED AGING

It is the time spent waiting in the latch while aging a deleted related dictionary cache.

LATCH: FILE MANAGER

It is the time spent waiting to acquire the latch for the file manager.

LATCH: TRACE LOG

It is the time spent waiting to acquire the latch for the trace log.

LATCH: STATIC HASH

It is the time spent waiting to acquire the latch for the static hash.

LATCH: STATIC HASH BUCKET

It is the time spent waiting to acquire the bucket latch for the static hash.

LATCH: SQL HANDLE

It is the time spent waiting to acquire the latch for the SQL cache manager.

LATCH: XA CONTEXT HASH

It is the time spent waiting to acquire the latch for the XA context hash.

LATCH: PLAN CLOCK

It is the time spent waiting to acquire the clock latch for the SQL plan.

LATCH: XA CONTEXT

It is the time spent waiting to acquire the latch for the XA context.

LATCH: MEM CONTROLLER

It is the time spent waiting to acquire the latch for the memory controller.

LATCH: DYNAMIC MEM

It is the time spent waiting to acquire the latch for dynamic memory.

LATCH: PROPERTY

It is the time spent waiting to acquire the latch for the property manager.

LATCH: ATTACH SHM

It is the time spent waiting to acquire the latch for the shared memory segment.

LATCH: BACKUP TBS

It is the time spent waiting to acquire the latch for the tablespace backup manager.

LATCH: DATABASE COMPONENT

It is the time spent waiting to acquire the latch for the datafile manager.

LATCH: TABLESPACE

It is the time spent waiting to acquire the latch for the tablespace.

LATCH: BACKUP DATABASE

It is the time spent waiting to acquire the latch for the database backup manager.

LATCH: JOURNAL BUFFER

It is the time spent waiting to acquire the latch for the journal buffer manager.

LATCH: JOURNAL BUFFER ENTRY

It is the time spent waiting to acquire the latch for the journal buffer entry.

LATCH: JOURNAL WRITE BUFFER

It is the time spent waiting to acquire the latch for the journal write buffer.

LATCH: LOCK ITEM

It is the time spent waiting to acquire the latch for the lock item.

LATCH: RECORD HASH

It is the time spent waiting to acquire the bucket latch for the lock record hash.

LATCH: SEQUENCE

It is the time spent waiting to acquire the latch for the sequence object.

LATCH: LOG FILE

It is the time spent waiting to acquire the latch for the redo logfile.

LATCH: BUILD AGABLE SCN

It is the time spent waiting for the latch to construct the agable SCN.

LATCH: TRANSACTION TABLE

It is the time spent waiting to acquire the latch for the transaction table.

LATCH: SESSION LINK HASH

It is the time spent waiting to acquire the bucket latch for the session link hash.

LATCH: ALLOC XA CONTEXT

It is the time spent waiting in the latch to allocate the XA context.

LATCH: SEQUENCE GLOBAL_X

It is the time spent waiting to acquire the X latch for the global sequence.

LATCH: SEQUENCE GLOBAL_Y

It is the time spent waiting to acquire the Y latch for the global sequence.

LATCH: TRANSACTION LOG FILE

It is the time spent waiting to acquire the latch for the transaction logfile.

ASYNC RESPONSE

It is the time spent waiting for a response to an asynchronous command from a remote node.
Parameter: None

ASYNC TRANSACTION

It is the time spent waiting for a response to an asynchronous COMMIT command from a remote node.
Parameter: None

LATCH: DISK BUFFER HASH BUCKET

It is the time spent waiting for the bucket latch for the hash of the disk buffer cache.

WRITE: CHANGE TRACKING FILE

It is the time spent waiting to acquire the latch for the change tracking file.
Parameter: None

WAIT FREE BUFFER

It is the time spent waiting to find a clean disk buffer.
Parameter: None

GLOBAL SEQUENCE: LOCK AND QUERY

It is the time spent waiting for the latch for global sequence synchronization.
Parameter: None

GLOBAL SEQUENCE: SYNC

It is the time spent waiting for the completion of global sequence synchronization.
Parameter: None

LATCH: SEQUENCE GLOBAL NEXT

It is the time spent waiting for the latch for sequence nextval.

LATCH: BUFFER LRU LIST

It is the time spent waiting for the latch for the LRU list of the disk buffer.

WAIT DIRTY PAGE LIMIT

It is the time spent waiting until the number of dirty pages in the disk buffer is reduced below the  BUFFER_DIRTY_PAGE_LIMIT property. 
Parameter: None

WAIT BUFFER READ COMPLETE

It is the time spent waiting for the read to complete when accessing a disk buffer page that is currently being read.
Parameter: None

WAIT ENV EVENT

It is the time spent waiting for the completion of the env event.

WAIT FREE APPEND EXTENT

It is the time spent waiting for the extent allocated for append insert to be freed in the buffer.
Parameter: None