Thanks, you solution works for most of the databases. But now I noticed that we have single 9.5 version also.
And seems like this function pg_size_bytes came from 9.6
# psql -U postgres -Atc "select pg_size_bytes(current_setting('shared_buffers'));" ERROR: function pg_size_bytes(text) does not exist LINE 1: select pg_size_bytes(current_setting('shared_buffers')); ^ HINT: No function matches the given name and argument types. You might need to add explicit type casts.
Do you perhaps happen to know a way how to get this to work in 9.5 also..?
Thanks again.
Regards
Raul
Kontakt Magnus Hagander (<magnus@hagander.net>) kirjutas kuupäeval K, 14. oktoober 2020 kell 18:38:
Magnus Hagander <magnus@hagander.net> writes: > On Wed, Oct 14, 2020 at 5:10 PM Tom Lane <tgl@sss.pgh.pa.us> wrote: >> It's fairly annoying that this doesn't work: >> regression=# select pg_size_bytes(setting||' '||unit) from pg_settings >> where name = 'shared_buffers';
> Actually thinking though, surely *this* particular case can be spelled as: > SELECT pg_size_bytes(current_setting('shared_buffers'))
Yeah, that might be the most recommendable way.
> Or if doing it off pg_settings: > SELECT setting::bigint * pg_size_bytes(unit) from pg_settings where > name='shared_buffers'
No, because that will fail for any unit other than '8kB', eg
Right, but it would certainly work for *this* case using pg_asettings, is what I meant.
That said, I think it'd then actually be better to teach pg_size_bytes to know that "MB" is the same as "1MB" and parse that. That might be something that would actually be useful in other cases as well -- basically as a way to get conversion units in general. Basically if the string is "unit only" then consider that as "1 unit".
