> [!ControlFileSyncUpdate] > <table><tr><td rowspan="4" width="25%"><img src="assets/wl_io_controlfilesyncupdate.png"></td><td><b>Wait Category</b></td><td>IO</td></tr><tr><td><b>Mechanism</b></td><td><code>pg_control</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/disk IO">disk IO</a>, <a href="Resources/CPU">CPU</a></td></tr><tr><td colspan="3"><b>State Transition Durability Barrier</b>. Every time the database changes its fundamental state—such as finishing a checkpoint, starting a base backup, or completing a recovery—it must write these changes to <code>pg_control</code> and ensure they are safe on disk before proceeding.</td></tr></table>