On Wed, Oct 14, 2020 at 5:23 PM Tom Lane <tgl@xxxxxxxxxxxxx> wrote:
Magnus Hagander <magnus@xxxxxxxxxxxx> writes:
> On Wed, Oct 14, 2020 at 5:10 PM Tom Lane <tgl@xxxxxxxxxxxxx> 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
regression=# select pg_size_bytes('MB');
ERROR: invalid size: "MB"
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".
