> [!DataFilePrefetch] > <table><tr><td rowspan="4" width="25%"><img src="assets/wl_io_datafileprefetch.png"></td><td><b>Wait Category</b></td><td>IO</td></tr><tr><td><b>Mechanism</b></td><td><code>DataFile</code></td></tr><tr><td><b>Operations</b></td><td><a href="Operations/Table/SeqScan">SeqScan</a>, <a href="Operations/Index/IndexScan">IndexScan</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>I/O Prediction Stutter</b>. Prefetching is an optimization where Postgres "looks ahead" in the query plan and tells the OS which pages it will need soon, hoping the hardware will have them ready before the engine actually asks for them.</td></tr></table>