A low-cardinality bucket name for a database query, for the same reason every other SDK's own transaction_name never uses the raw SQL text directly: every slightly different query shape would become its own bucket, and raw SQL is a real, if usually parameterized, risk of leaking a literal value.

source (the table name) is passed separately from sql, not extracted from it, because Ecto.Adapters.SQL's own [:query] telemetry event already hands over the table name directly in metadata.source for any query built from Ecto.Query, the common case: no regex needed there at all, unlike every other language's own DB integration in this repo so far. source is only nil for a raw SQL call (Ecto.Adapters.SQL.query!/4 and friends), which is where the regex fallback below, a direct port of the identical one already written for the Python and PHP SDKs this session, actually does something: extracts "<VERB> <table>" ("SELECT auth_user", "INSERT INTO orders") for the two shapes that carry a table name in a predictable place, falling back to just the first SQL keyword ("PRAGMA", "BEGIN") for anything else, or the literal string "SQL" if even that fails.