Re: Parameter value from (mb/gb) to bytes

Hi

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(at)hagander(dot)net>) kirjutas kuupäeval K, 14.
oktoober 2020 kell 18:38:

>
>
> On Wed, Oct 14, 2020 at 5:23 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
>> Magnus Hagander <magnus(at)hagander(dot)net> writes:
>> > On Wed, Oct 14, 2020 at 5:10 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)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
>>
>> 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".
>
> --
> Magnus Hagander
> Me: https://www.hagander.net/ <http://www.hagander.net/>
> Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>
>