Updated on 2024-05-07 GMT+08:00

LOCKS

LOCKS displays information about locks held by each open transaction.

Table 1 LOCKS columns

Name

Type

Description

locktype

text

Type of the locked object: relation, extend, page, tuple, transactionid, virtualxid, object, userlock, or advisory

database

oid

OID of the database in which the locked object exists.
  • The OID is 0 if the object is a shared object.
  • The OID is NULL if the object is a transaction ID.

relation

oid

OID of the relationship targeted by the lock. The value is NULL if the object is not a relationship or part of a relationship.

page

integer

Page number targeted by the lock within the relationship. The value is NULL if the object is not a relationship page or row page.

tuple

smallint

Row number targeted by the lock within the page. The value is NULL if the object is not a row.

bucket

integer

Hash bucket ID.

virtualxid

text

Virtual ID of the transaction targeted by the lock. The value is NULL if the object is not a virtual transaction ID.

transactionid

xid

ID of the transaction targeted by the lock. The value is NULL if the object is not a transaction ID.

classid

oid

OID of the system catalog that contains the object. The value is NULL if the object is not a general database object.

objid

oid

OID of the locked object within its system catalog. The value is NULL if the object is not a general database object.

objsubid

smallint

Column number for a column in the table (0 if the object is of other object type and NULL if the object is not a general database object)

virtualtransaction

text

Virtual ID of the transaction holding or awaiting this lock

pid

bigint

Logical ID of the server thread holding or awaiting this lock. The value is NULL if the lock is held by a prepared transaction.

sessionid

bigint

ID of the session holding or awaiting this lock The value is NULL if the lock is held by a prepared transaction.

mode

text

Lock mode held or desired by this thread

granted

Boolean

  • The value is TRUE if the lock is a held lock.
  • The value is FALSE if the lock is an awaited lock.

fastpath

Boolean

The value is TRUE if the lock is obtained through fast-path, and is FALSE if the lock is obtained through the main lock table.

locktag

text

Lock information that the session waits for. It can be parsed using the locktag_decode() function.

global_sessionid

text

Global session ID