> [!XactBuffer] > <table><tr><td rowspan="4" width="25%"><img src="assets/wl_lw_xactbuffer.png"></td><td><b>Wait Category</b></td><td>LWLock</td></tr><tr><td><b>Mechanism</b></td><td><code>XactBufferLock</code></td></tr><tr><td><b>Operations</b></td><td><a href="Operations/Tuple/ModifyTable">ModifyTable</a>, <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">Contention on the <b>Transaction Visibility Layer</b>. The Xact SLRU (historically called the CLOG) is a critical shared-memory cache that stores the final status for every transaction ID (XID), indicating if it is <code>COMMITTED</code>, <code>ABORTED</code>, or still <code>IN_PROGRESS</code>.</td></tr></table>