Another useful tool for monitoring database activity is the
pg_locks system table. It allows the
database administrator to view information about the outstanding
locks in the lock manager. For example, this capability can be used
to:
View all the locks currently outstanding, all the locks on
relations in a particular database, all the locks on a
particular relation, or all the locks held by a particular
PostgreSQL session.
Determine the relation in the current database with the most
ungranted locks (which might be a source of contention among
database clients).
Determine the effect of lock contention on overall database
performance, as well as the extent to which contention varies
with overall database traffic.
Details of the pg_locks view appear in
Section 44.46.
For more information on locking and managing concurrency with
PostgreSQL, refer to Chapter 13.
