Am Dienstag, den 21.03.2017, 15:34 -0400 schrieb Robert Haas: > On Sun, Mar 19, 2017 at 12:01 PM, Magnus Hagander <mag...@hagander.net> wrote: > > I think maybe we should output a message when the slot is created, at least > > in verbose mode, to make sure people realize that happened. Does that seem > > reasonable? > > Slots are great until you leave one lying around by accident. I'm > afraid that no matter what we do, we're going to start getting > complaints from people who mess that up. For example, somebody > creates a replica using the new super-easy method, and then blows it > away without dropping the slot from the master, and then days or weeks > later pg_wal fills up and takes the server down. The user says, oh, > these old write-ahead log files should have gotten removed, and > removes them all. Oops.
Hrm. Maybe it would be useful to log a warning like "slot XY has not been active for X minutes", based on some threshold, though possibly the people not keeping an eye on their replication slots won't spot that in the logfiles, either. > So I tend to think that there should always be some explicit user > action to cause the creation of a slot, like --create-slot-if-needed > or --create-slot=name. That still won't prevent careless use of that > option but it's less dangerous than assuming that a user who refers to > a nonexistent slot intended to create it when, perhaps, they just > typo'd it. I guess if we decide (physical) slots should not be created implicitly, then using the same UI as pg_receivewal makes sense for the sake of consistency, i.e. "--slot=name --create-slot [--if-not-exists]". That is rather verbose though and I don't think the --if-not-exists is great UX, but maybe there is some use-case for erroring out if a slot already exists that I haven't thought of. Michael -- Michael Banck Projektleiter / Senior Berater Tel.: +49 2166 9901-171 Fax: +49 2166 9901-100 Email: michael.ba...@credativ.de credativ GmbH, HRB Mönchengladbach 12080 USt-ID-Nummer: DE204566209 Trompeterallee 108, 41189 Mönchengladbach Geschäftsführung: Dr. Michael Meskes, Jörg Folz, Sascha Heuer -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers