The reason for my original email (a month ago) is that I couldn't find any information about that in the documentation. Have I missed it? Has the documentation changed since? Given the lack of response in this thread, I assumed not. My question was *what should I expect*, not that there was a bug in either doc or code. (unless one considers *lack of information* in the doc a bug.) And to complicate matters, the transaction could mix DBs in Journal and WAL mode too. I also do not recall reading anything about that case either, although again I could well have missed it. And why I'm asking these questions here. SQLite's documentation tends to be very exhaustive about when something is *undefined behavior* or not; and since it does not say anything (that I know of) in these particular cases (begin+attach, or attach-Journal + attach+WAL), I guess one *could assume* both are supported, but given these are *corner cases* I never thought about before, nor remember reading anything about in the doc or the ML/forum I prefer to ask the experts. Unlike me, you know whether there are unit tests for these use-cases, for example.