> [!DataFileRead] > <table><tr><td rowspan="4" width="25%"><img src="assets/wl_io_datafileread.png"></td><td><b>Wait Category</b></td><td>IO</td></tr><tr><td><b>Mechanism</b></td><td><code>FileRead</code></td></tr><tr><td><b>Operations</b></td><td><a href="Operations/Table/SeqScan">SeqScan</a>, <a href="Operations/Index/IndexScan">IndexScan</a>, <a href="Operations/Page/BitmapHeapScan">BitmapHeapScan</a>, <a href="Operations/Index/IndexOnlyScan">IndexOnlyScan</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">This wait event represents a synchronous stall while the backend process waits for the operating system to deliver a data page from the physical storage medium. When the engine encounters a buffer miss in <b>Shared Buffers</b>, it must issue a system call to the kernel to read the 8KB block from the relation data files.</td></tr></table>