> [!WalSenderWaitWal] > <table><tr><td rowspan="4" width="25%"><img src="assets/wl_activity_walsenderwaitwal.png"></td><td><b>Wait Category</b></td><td>Activity</td></tr><tr><td><b>Mechanism</b></td><td><code>WalSenderWaitForWAL</code></td></tr><tr><td><b>Operations</b></td><td><a href="Operations/Distributed/Redistribute">Redistribute</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>Primary-Side Durability Lag</b>. To ensure data integrity, a WAL Sender cannot stream records that have not yet been durably persisted to the primary's own <code>pg_wal</code> directory.</td></tr></table>