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<title>24.3.Viewing Locks</title>
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<a name="monitoring-locks"></a>24.3.Viewing Locks</h2></div></div></div>
<a name="id673120"></a><p> Another useful tool for monitoring database activity is the
<code class="structname">pg_locks</code> 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:
</p>
<div class="itemizedlist"><ul type="disc">
<li><p> 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
<span class="productname">PostgreSQL</span> session.
</p></li>
<li><p> Determine the relation in the current database with the most
ungranted locks (which might be a source of contention among
database clients).
</p></li>
<li><p> Determine the effect of lock contention on overall database
performance, as well as the extent to which contention varies
with overall database traffic.
</p></li>
</ul></div>
<p>
Details of the <code class="structname">pg_locks</code> view appear in
<a href="view-pg-locks.html" title="42.37.pg_locks">Section42.37, “<code class="structname">pg_locks</code>”</a>.
For more information on locking and managing concurrency with
<span class="productname">PostgreSQL</span>, refer to <a href="mvcc.html" title="Chapter12.Concurrency Control">Chapter12, <i>Concurrency Control</i></a>.
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