PG_LOCKS

PG_LOCKS displays information about the locks held by open transactions.

**Table 1** PG_LOCKS columns
Column	Type	Reference	Description
locktype	Text	N/A	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	N/A	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	N/A	Row number targeted by the lock within the page. If the object is not a row, the value is NULL.
virtualxid	Text	N/A	Virtual ID of the transaction targeted by the lock. If the object is not a virtual transaction ID, the value is NULL.
transactionid	Xid	N/A	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	N/A	OID of the lock target within its system table. If the target is not a general database object, the value is NULL.
objsubid	Smallint	N/A	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	N/A	Virtual ID of the transaction holding or awaiting this lock
pid	Bigint	N/A	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	N/A	Lock mode held or desired by this thread For more information about lock modes, see LOCK.
granted	boolean	N/A	The value is true if the lock is a held lock. The value is false if the lock is an awaited lock.
fastpath	boolean	N/A	Whether the lock is obtained through fast-path (true) or main lock table (false)
waittime	Timestamp with time zone	N/A	Timestamp when the lock wait starts. This column is available only in clusters of version 9.1.0.200 or later.
holdtime	Timestamp with time zone	N/A	Timestamp when the lock starts to be held. This column is available only in clusters of version 9.1.0.200 or later.