When you create an external table using USING CSV LOCATION '/path', Spark reads data from the file but doesn’t manage the files or modify them when new data is inserted.

When you use INSERT INTO on an external table, Spark stores the new data in its internal metadata (e.g., Hive Metastore), not in the original CSV file.

Spark treats CSV as read-only and doesn’t append records to it. Instead, the new data is stored in Spark's managed storage, allowing it to be queried but not reflected in the CSV.

To write new data back to files, you’ll need to either convert the table to a managed table or write the updated data to a new location.