I'd expect transactions left open on DB conn close to be rolled back, having not received the "COMMIT" call which can now never come by the very fact of the DB conn being closed now. If closing the DB conn auto-commits all still-open transactions under the Tcl SQLite binding, I'd call that a bug, not a feature. The semantic meaning of transactions is that those not explicitly committed get rolled back, but once again, that can't happen with the conn closed.