BLOB_DESCRIPTOR - LanceDB

Applies to: Embedded ❌, Enterprise ✅

SELECT id, blob_descriptor(video) AS descriptor FROM videos

A BlobV2 column’s bytes are not fetched by a plain SELECT: that already returns large_binary, the same as any other binary column. blob_descriptor instead returns a small struct describing where the payload lives, without reading it. Pass one row’s descriptor to the SDK’s blob file reader to open that payload directly:

rows = db.execute_query("SELECT id, blob_descriptor(video) AS descriptor FROM videos").read_all().to_pylist()
with table.open_blob_file(rows[0]["descriptor"]) as reader:
    payload = reader.read()

A descriptor is pinned to the table version it was read at: it keeps resolving correctly even after the table is appended to and checked out to a newer version.

What to read next

Managed blobs

The BlobV2 column type this function describes.