> [!RestoreCommand] > <table><tr><td rowspan="4" width="25%"><img src="assets/wl_ipc_restorecommand.png"></td><td><b>Wait Category</b></td><td>IPC</td></tr><tr><td><b>Mechanism</b></td><td><code>restore_command</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/Network">Network</a>, <a href="Resources/CPU">CPU</a></td></tr><tr><td colspan="3"><b>External Log Retrieval Delay</b>. When a standby needs a WAL segment that is no longer in the primary's <code>pg_wal/</code> directory, it must call an external script to "fetch" it from the persistent archive (e.g., S3, GCS, or a network mount).</td></tr></table>