![[assets/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**: - [[Operations/Hash]] - [[Operations/Materialize]] - [[Operations/HashJoin]] - [[Operations/CTEScan]] - [[Operations/MergeJoin]] - [[Operations/WindowAgg]] - [[Operations/RecursiveUnion]] - [[Operations/Aggregate]] - [[Operations/SetOp]] - [[Operations/Sort]] - **Resources**: [[Resources/disk IO]], [[Resources/CPU|CPU]]