Bryn Llewellyn wrote: > B.t.w., I’m guessing that the “begin” SQL command that you see in the log > that I mentioned is actually issued by (some) clients—at least psql and > Python-on-psycopg2—as an explicit call from the client. In other words, it > isn’t the server that generates this. Does anyone know for sure how this > works? Well, that's the point of Autocommit, and moreover it does nothing else. Maybe you're still confused about this. * Autocommit off = the client automatically adds a "BEGIN" when it thinks a transaction must be started on behalf of the user. * Autocommit on = the client does nothing. The fact that "off" implies doing something and "on" implies not interfering is counterintuitive, but that's how it is. Autocommit is for compatibility with other databases. If it was only for Postgres, I guesss either it wouldn't exist in the first place or it should be called "AutoStartTransactionBlock" or something like that, because that's just what it really does. Anyway, the server only know whether a BEGIN has been issued. It never knows or cares whether it has been added implicitly or explicitly, which is why it can be quite confusing to reason about server-side differences in terms of Autocommit, as you do in some of your previous messages. It should be stressed that Autocommit is not a parameter of the session between Postgres and the SQL client, but rather it's a parameter of the session between the user and their SQL client. So when you're hypothesizing that a plpgsql block in a procedure would look at this parameter or change it temporarily (your points #2 and #5 in your analysis of p2's execution), you should see that it's impossible, because on the server-side, this parameter just does not exist. Best regards, -- Daniel Vérité PostgreSQL-powered mailer: http://www.manitou-mail.org Twitter: @DanielVerite
