【DOC】VIEW: "V$LOCK" Reference Note

Subject:	VIEW: "V$LOCK" Reference Note
	Doc ID:	29787.1	Type:	REFERENCE
	Modified Date:	11-NOV-2002	Status:	PUBLISHED

"V$LOCK" Reference Note

• The information here contains the view description from the Oracle9i documentation along with any additional related to this view.
• Earlier versions of Oracle may not include all columns.

Oracle9i Information

• This view lists the locks currently held by the Oracle server and outstanding requests for a lock or latch.

  Column  Datatype  Description 

  ADDR 

  RAW(4) 

  Address of lock state object 

  KADDR 

  RAW(4) 

  Address of lock 

  SID 

  NUMBER 

  Identifier for session holding or acquiring the lock 

  TYPE 

  VARCHAR2(2) 

  Type of user or system lock

  The locks on the user types are obtained by user applications. Any process that is blocking others is likely to be holding one of these locks. The user type locks are:

  TM - DML enqueue

  TX - Transaction enqueue

  UL - User supplied

  The locks on the system types are held for extremely short periods of time.

  ID1 

  NUMBER 

  Lock identifier #1 (depends on type) 

  ID2 

  NUMBER 

  Lock identifier #2 (depends on type) 

  LMODE 

  NUMBER 

  Lock mode in which the session holds the lock:

  • 0 - none

  • 1 - null (NULL)

  • 2 - row-S (SS)

  • 3 - row-X (SX)

  • 4 - share (S)

  • 5 - S/Row-X (SSX)

  • 6 - exclusive (X)

   

  REQUEST  

  NUMBER 

  Lock mode in which the process requests the lock:

  • 0 - none

  • 1 - null (NULL)

  • 2 - row-S (SS)

  • 3 - row-X (SX)

  • 4 - share (S)

  • 5 - S/Row-X (SSX)

  • 6 - exclusive (X)

   

  CTIME 

  NUMBER 

  Time since current mode was granted 

  BLOCK 

  NUMBER 

  The lock is blocking another lock 

  Table 3-1  Values for the TYPE Column: System Types

  System Type	Description	System Type	Description
  BL	Buffer hash table instance	NA..NZ	Library cache pin instance (A..Z = namespace)
  CF	Control file schema global enqueue	PF	Password File
  CI	Cross-instance function invocation instance	PI, PS	Parallel operation
  CU	Cursor bind	PR	Process startup
  DF	Data file instance	QA..QZ	Row cache instance (A..Z = cache)
  DL	Direct loader parallel index create	RT	Redo thread global enqueue
  DM	Mount/startup db primary/secondary instance	SC	System commit number instance
  DR	Distributed recovery process	SM	SMON
  DX	Distributed transaction entry	SN	Sequence number instance
  FS	File set	SQ	Sequence number enqueue
  HW	Space management operations on a specific segment	SS	Sort segment
  IN	Instance number	ST	Space transaction enqueue
  IR	Instance recovery serialization global enqueue	SV	Sequence number value
  IS	Instance state	TA	Generic enqueue
  IV	Library cache invalidation instance	TS	Temporary segment enqueue (ID2=0)
  JQ	Job queue	TS	New block allocation enqueue (ID2=1)
  KK	Thread kick	TT	Temporary table enqueue
  LA .. LP	Library cache lock instance lock (A..P = namespace)	UN	User name
  MM	Mount definition global enqueue	US	Undo segment DDL
  MR	Media recovery	WL	Being-written redo log instance

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