Re: pg_sequence_last_value() for unlogged sequences on standbys
От | Nathan Bossart |
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Тема | Re: pg_sequence_last_value() for unlogged sequences on standbys |
Дата | |
Msg-id | 20240501011317.GC594666@nathanxps13 обсуждение исходный текст |
Ответ на | Re: pg_sequence_last_value() for unlogged sequences on standbys (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: pg_sequence_last_value() for unlogged sequences on standbys
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Список | pgsql-hackers |
On Tue, Apr 30, 2024 at 09:06:04PM -0400, Tom Lane wrote: > Nathan Bossart <nathandbossart@gmail.com> writes: >> If you create an unlogged sequence on a primary, pg_sequence_last_value() >> for that sequence on a standby will error like so: >> postgres=# select pg_sequence_last_value('test'::regclass); >> ERROR: could not open file "base/5/16388": No such file or directory > >> As pointed out a few years ago [0], this function is undocumented, so >> there's no stated contract to uphold. I lean towards just returning NULL >> because that's what we'll have to put in the relevant pg_sequences field >> anyway, but I can see an argument for fixing the ERROR to align with what >> you see when you try to access unlogged relations on a standby (i.e., >> "cannot access temporary or unlogged relations during recovery"). > > Yeah, I agree with putting that logic into the function. Putting > such conditions into the SQL of a system view is risky because it > is really, really painful to adjust the SQL in a released version. > You could back-patch a fix for this if done at the C level, but > I doubt we'd go to the trouble if it's done in the view. Good point. I'll work on a patch along these lines, then. -- Nathan Bossart Amazon Web Services: https://aws.amazon.com
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