> laurenz.a...@cybertec.at wrote: > > Be "seeing" I didn't mean "show to the user". I mean that the code that > implements PostgreSQL constraints takes uncommitted data into account. > > The documentation describes that for the case of uniqueness in some detail: > > https://www.postgresql.org/docs/current/index-unique-checks.html > > I'd say that the proper mental model is that you don't need to care. The ACID > properties are guarantees that the database makes, and these guarantees are > usually negative: "no sequence of actions can result in the violation of a > unique constraint" or "you don't get to see uncommitted data". > > The exact sequence of what happens during COMMIT is interesting, but > irrelevant to the programmer. All that counts is "a deferred constraint is > checked between the time that COMMIT starts processing and the time that it > returns". > > If you want to know more, you have to start reading the code. It is open > source and well documented.
Thanks for the quick reply, Laurenz. I'm signing off now (US/Pacific) for a long weekend. I'll try to digest what you wrote on Monday.
