I was also thinking about this use case when reading the announcement. Let's say you have a bunch of parquet files already (on local FS, HTTPS, S3, ...) that you can assume are immutable (or maybe append-only). It would be great if you could attach them to the DuckLake without copying them! From the design doc, it seems it should essentially work, you would read those parquet files to compute the metadata, and insert a reference to the parquet file instead of copying them to the storage you manage. Basically you want to create the catalog independently from the underlying data.