PG_LOCKS

PG_LOCKS displays information about the locks held by open transactions.

**Table 1** PG_LOCKS columns
Name	Type	Reference	Description
locktype	text	-	Type of the locked object: relation, extend, page, tuple, transactionid, virtualxid, object, userlock, and advisory
database	oid	PG_DATABASE.oid	OID of the database in which the locked target exists The OID is 0 if the target is a shared object. The OID is NULL if the locked target is a transaction.
relation	oid	PG_CLASS.oid	OID of the relationship targeted by the lock. The value is NULL if the object is neither a relationship nor part of a relationship.
page	integer	-	Page number targeted by the lock within the relationship. If the object is neither a relation page nor row page, the value is NULL.
tuple	smallint	-	Row number targeted by the lock within the page. If the object is not a row, the value is NULL.
virtualxid	text	-	Virtual ID of the transaction targeted by the lock. If the object is not a virtual transaction ID, the value is NULL.
transactionid	xid	-	ID of the transaction targeted by the lock. If the object is not a transaction ID, the value is NULL.
classid	oid	PG_CLASS.oid	OID of the system table that contains the object. If the object is not a general database object, the value is NULL.
objid	oid	-	OID of the lock target within its system table. If the target is not a general database object, the value is NULL.
objsubid	smallint	-	Column number for a column in the table. The value is 0 if the target is some other object type. If the object is not a general database object, the value is NULL.
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. This is NULL if the lock is held by a prepared transaction.
mode	text	-	Lock mode held or desired by this thread For more information about lock modes, see LOCK.
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	-	Whether the lock is obtained through fast-path (true) or main lock table (false)