![[wl_io_buffilewrite.png|256]] - **Description**: Signifies that temporary files are being written (or "spilled") to disk because the in-memory buffers are full. This is often caused by SQL queries that require more memory than configured by `work_mem` or `maintenance_work_mem`. - **Operations**: - [[Hash]] - [[Materialize]] - [[HashJoin]] - [[CTEScan]] - [[MergeJoin]] - [[WindowAgg]] - [[RecursiveUnion]] - [[Aggregate]] - [[SetOp]] - [[Sort]] - **Resources**: [[Disk IO]], [[CPU]]