> [!WALBufMapping] > <table><tr><td rowspan="4" width="25%"><img src="assets/wl_lwlock_wal_mapping.png"></td><td><b>Wait Category</b></td><td>LWLock</td></tr><tr><td><b>Mechanism</b></td><td><code>WALBufMapping</code></td></tr><tr><td><b>Operations</b></td><td><a href="Operations/Other/WAL">WAL Write</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 <b>WAL Page Allocation</b>. This lock is acquired when a backend process needs to replace a page in the WAL buffers, typically because the buffer is full and must be flushed to disk before new data can be written.</td></tr></table>