syslockinfo

Transact-SQL Reference

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Transact-SQL Reference

syslockinfo

Contains information on all granted, converting, and waiting lock requests. This table is a denormalized tabular view of internal data structures of the lock manager, and is stored only in the master database.

Column name Data type Description
rsc_text nchar(32) Textual description of a lock resource. Contains a portion of the resource name.
rsc_bin binary(16) Binary lock resource. Contains the actual lock resource that is contained in the lock manager. This column is included for tools that are aware of the lock resource format for generating their own formatted lock resource, and for performing self joins on syslockinfo.
rsc_valblk binary(16) Lock value block. Some resource types may include additional data in the lock resource that is not hashed by the lock manager to determine ownership of a particular lock resource. For example, page locks are not owned by a particular object ID. For lock escalation and other purposes, however, the object ID of a page lock may be placed in the lock value block.
rsc_dbid smallint Database ID associated with the resource.
rsc_indid smallint Index ID associated with the resource, if appropriate.
rsc_objid int Object ID associated with the resource, if appropriate.
rsc_type tinyint Resource type. Can be:

1 = NULL Resource (not used).
2 = Database.
3 = File.
4 = Index.
5 = Table.
6 = Page.
7 = Key.
8 = Extent.
9 = RID (Row ID).
10 = Application.
rsc_flag tinyint Internal resource flags.
req_mode tinyint Lock request mode. This column is the lock mode of the requester and represents either the granted mode, or the convert or waiting mode. Can be:

0 = NULL. No access is granted to the resource. Serves as a placeholder.
1 = Sch-S (Schema stability). Ensures that a schema element, such as a table or index, is not dropped while any session holds a schema stability lock on the schema element.
2 = Sch-M (Schema modification). Must be held by any session that wants to change the schema of the specified resource. Ensures that no other sessions are referencing the indicated object.
3 = S (Shared). The holding session is granted shared access to the resource.
4 = U (Update). Indicates an update lock acquired on resources that may eventually be updated. It is used to prevent a common form of deadlock that occurs when multiple sessions lock resources for potential update at a later time.
5= X (Exclusive). The holding session is granted exclusive access to the resource.
6 = IS (Intent Shared). Indicates the intention to place S locks on some subordinate resource in the lock hierarchy.
7= IU (Intent Update). Indicates the intention to place U locks on some subordinate resource in the lock hierarchy.
8= IX (Intent Exclusive). Indicates the intention to place X locks on some subordinate resource in the lock hierarchy.
9 = SIU (Shared Intent Update). Indicates shared access to a resource with the intent of acquiring update locks on subordinate resources in the lock hierarchy.
10 = SIX (Shared Intent Exclusive). Indicates shared access to a resource with the intent of acquiring exclusive locks on subordinate resources in the lock hierarchy.
11 = UIX (Update Intent Exclusive). Indicates an update lock hold on a resource with the intent of acquiring exclusive locks on subordinate resources in the lock hierarchy.
12 = BU. Used by bulk operations.
13 = RangeS_S (Shared Key-Range and Shared Resource lock). Indicates serializable range scan.
14 = RangeS_U (Shared Key-Range and Update Resource lock). Indicates serializable update scan.
15 = RangeI_N (Insert Key-Range and Null Resource lock). Used to test ranges before inserting a new key into an index.
16 = RangeI_S. Key-Range Conversion lock, created by an overlap of RangeI_N and S locks.
17 = RangeI_U. Key-Range Conversion lock, created by an overlap of RangeI_N and U locks.
18 = RangeI_X. Key-Range Conversion lock, created by an overlap of RangeI_N and X locks.
19 = RangeX_S. Key-Range Conversion lock, created by an overlap of RangeI_N and RangeS_S. locks.
20 = RangeX_U. Key-Range Conversion lock, created by an overlap of RangeI_N and RangeS_U locks.
21 = RangeX_X (Exclusive Key-Range and Exclusive Resource lock). This is a conversion lock used when updating a key in a range.
req_status tinyint Status of the lock request. Can be:

1 = Granted.
2 = Converting.
3 = Waiting.
req_refcnt smallint Lock reference count. Each time a transaction asks for a lock on a particular resource, a reference count is incremented. The lock cannot be released until the reference count equals 0.
req_cryrefcnt smallint Reserved for future used. Always set to 0.
req_lifetime int Lock lifetime bitmap. During certain query processing strategies, locks must be maintained on resources until the query processor has completed a particular phase of the query. The lock lifetime bitmap is used by the query processor and transaction manager to denote groups of locks that can be released when a certain phase of a query is completed. Certain bits in the bitmap are used to denote locks that are held until the end of a transaction, even if their reference count equals 0.
req_spid int Internal Microsoft® SQL Server™ process ID of the session requesting the lock.
req_ecid int Execution context ID (ECID). Used to denote which thread in a parallel operation owns a particular lock.
req_ownertype smallint Type of object associated with the lock. Can be one of the following:

1 = Transaction.
2 = Cursor.
3 = Session.
4 = ExSession.

Note that 3 and 4 represent a special version of session locks, tracking database and filegroup locks respectively.
req_transactionID bigint Unique transaction ID used in syslockinfo and in profiler event
req_transactionUOW uniqueidentifier Identifies the Unit of Work ID (UOW) of the DTC transaction. For non MS DTC transactions, UOW is set to 0.

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