> [!userlock] > <table><tr><td rowspan="4" width="25%"><img src="assets/wl_lock_userlock.png"></td><td><b>Wait Category</b></td><td>Lock</td></tr><tr><td><b>Mechanism</b></td><td><code>UserLock</code></td></tr><tr><td><b>Operations</b></td><td><a href="Operations/Table/SeqScan">SeqScan</a></td></tr><tr><td><b>Resources</b></td><td><a href="Resources/RAM">Memory</a>, <a href="Resources/CPU">CPU</a></td></tr><tr><td colspan="3"><b>Application-Layer Coordination Barrier</b>. User locks were the precursor to modern <code>advisory</code> locks and are managed via a similar ID-based system.</td></tr></table>