> [!ProcArray] > <table><tr><td rowspan="4" width="25%"><img src="assets/wl_lw_procarray.png"></td><td><b>Wait Category</b></td><td>LWLock</td></tr><tr><td><b>Mechanism</b></td><td><code>ProcArrayLock</code></td></tr><tr><td><b>Operations</b></td><td><a href="Operations/Table/SeqScan">SeqScan</a>, <a href="Operations/Tuple/ModifyTable">ModifyTable</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">Contention on the <b>Global Visibility Coordinator</b>. Every time a query starts, it must take a "Snapshot" to determine which transactions were already committed and which are still in-flight; this requires scanning the entire <code>ProcArray</code> while holding this lock.</td></tr></table>