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v5.0

Documentation:v5.0

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PG_LOCKS

PG_LOCKS displays information about 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, or advisory
database oid PG_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 PG_CLASS.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 relation (NULL if the object is not a relation page or row page)
tuple smallint - Row number targeted by the lock within the page (NULL if the object is not a row)
bucket integer - Bucket number corresponding to the child table. The value is NULL if the target is not a table.
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 PG_CLASS.oid OID of the system catalog that contains the object (NULL if the object is not a general database object)
objid oid - OID of the lock target within its system table (NULL if the target is not a general database object)
objsubid smallint - Column number for a column in the table. The value is 0 if the object is some other object type. The value is 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 (NULL if the lock is held by a prepared transaction)
sessionid bigint - ID of the session holding or awaiting this lock
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
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