Oracle Server Manager User's Guide

The Lock Monitor

The Lock Monitor displays information about locks that are held and locks that are requested.

The following figure illustrates the left-most columns of the Lock Monitor.

Figure 11 - 6. Lock Monitor

The Lock Monitor is described below:

Username Oracle user associated with the session that is holding or requesting the lock.
Session ID Identifier for the session that is holding or requesting the lock.
Serial Number Session serial number, used to uniquely identify a session's objects. Guarantees that session-level commands are applied to the correct session objects if the session ends and another session begins with the same session identifier.
Lock Type Type of lock being held or requested. User locks, which are locks obtained by user applications, are described below:
TM DML enqueue lock.
TX Transaction enqueue lock.
UL User supplied lock.
All other locks are system locks, which are held for extremely short periods of time.
Resource ID 1 Identifier for resource being locked.
Resource ID 2 Additional identifier for resource being locked.
Mode Held Mode in which the lock is held, or NONE if waiting for the lock. The lock modes are described below:
SS Row share.
SX Row exclusive.
S Share.
SSX Share row exclusive.
X Exclusive.
Mode Requested Mode in which lock has been requested, or NONE if the lock has been acquired. See the lock modes defined above.

Filters

The following filter is available in the Lock Monitor:

Username Filter for the user associated with the session that is holding or requesting the lock. Monitor displays lock information only for users whose names match the Username filter.

SQL Worksheet Equivalent

To start the Lock Monitor from a SQL Worksheet, you can use the following Server Manager command:

	MONITOR LOCK

Required Views

To use the Lock Monitor, you must have access to:

V$LOCK

V$SESSION

Username	Oracle user associated with the session that is holding or requesting the lock.
Session ID	Identifier for the session that is holding or requesting the lock.
Serial Number	Session serial number, used to uniquely identify a session's objects. Guarantees that session-level commands are applied to the correct session objects if the session ends and another session begins with the same session identifier.
Lock Type	Type of lock being held or requested. User locks, which are locks obtained by user applications, are described below:
	TM DML enqueue lock.
	TX Transaction enqueue lock.
	UL User supplied lock.
	All other locks are system locks, which are held for extremely short periods of time.
Resource ID 1	Identifier for resource being locked.
Resource ID 2	Additional identifier for resource being locked.
Mode Held	Mode in which the lock is held, or NONE if waiting for the lock. The lock modes are described below:
	SS Row share.
	SX Row exclusive.
	S Share.
	SSX Share row exclusive.
	X Exclusive.
Mode Requested	Mode in which lock has been requested, or NONE if the lock has been acquired. See the lock modes defined above.