> [!XactTruncation] > <table><tr><td rowspan="4" width="25%"><img src="assets/wl_lw_xacttruncation.png"></td><td><b>Wait Category</b></td><td>LWLock</td></tr><tr><td><b>Mechanism</b></td><td><code>XactTruncationLock</code></td></tr><tr><td><b>Operations</b></td><td><a href="Operations/Table/SeqScan">SeqScan</a>, <a href="Operations/ResultSet/Materialize">Materialize</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">This wait event represents a <b>Transaction History Cleanup Barrier</b>. As Transaction IDs (XIDs) advance, the engine no longer needs to track the status of very old transactions.</td></tr></table>