Yes, I do believe that I understand this. But there’s no getting away from the fact that the AUTOCOMMIT mode, and what this implies, is a server-side phenomenon—at least as several PostgreSQL experts have assured me. For example, when you use client-side Python with the psycopg2 driver, then once you’ve done “my_session = psycopg2.connect(connect_str)”, you can then do “my_session.set_session(autocommit=False)”. And then everything we’ve been saying in the psql context now applies in that context—yes?
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? On 07-Aug-2019, at 11:56, Adrian Klaver <adrian.kla...@aklaver.com> wrote: On 8/7/19 11:46 AM, Bryn Llewellyn wrote: > Thanks for your response, Kyotaro. I’m happy, now, to accept the rule that > “call proc_that_does_txn_control()” is legal only when AUTOCOMMIT is ON. Esp. > when I’m told (on twitter, by 2ndQuadrant’s Peter Eisentraut, that this rule > is “an implementation restriction, for the most part.” See HERE > <https://twitter.com/petereisentraut/status/1158802910865756160>. > About your “In-procedure transaction control premises that no transaction is > active before calling the procedure”… yes. Nevertheless, as the code that > Umair Sahid showed us in the blog post that I referenced in my email that > started this thread, you can indeed start end end transactions from an > executing proc (as long as the session’s AUTOCOMMIT mode s ON). The key is that the AUTOCOMMIT status is just a specific case of the general rule. The general rule being that a PROCEDURE cannot do transaction ending commands when it it called within an outer transaction. You can run into the same issue in other situations e.g. ORM's that start a transaction behind the scenes. In other words this is not psql specific. As long as you understand the general rule then things become clearer. -- Adrian Klaver adrian.kla...@aklaver.com
