Re: Monitoring disk space from within the server

On Fri, Nov 8, 2019 at 2:58 PM Christoph Berg <myon(at)debian(dot)org> wrote:
>
> Re: Julien Rouhaud 2019-11-08 <CAOBaU_Zu6RP6-mHyA_J9-xkxJe0tarTVqU9TFza+tCPKUxsjiA(at)mail(dot)gmail(dot)com>
> > The related function on Windows is apparently GetDiskFreeSpaceA [1].
>
> There's a link to GetDiskFreeSpaceExA() which seems much easier to use
> because it accepts any directory on the drive in question:
>
> https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-getdiskfreespaceexa
>
> > It'll probably be quite hard to get something consistent for most of
> > counters, so probably pg_tablespace_(disk_)space is the best name,
> > providing only total size and free size?
>
> So, how about:
>
> pg_tablespace_disk_space -> total_bytes | free_bytes
>
> The inode numbers are probably not very interesting in a PG tablespace
> as we don't create that many files. Or do we think including these
> counters (on UNIX) makes sense?

Agreed, inodes are probably not very useful there.

> There's precedents for leaving fields NULL where not supported by the
> OS, for example pg_stat_file() returns "change" on UNIX only, and
> "creation" on Windows only.
> [...]
> Given that PG deals badly with one tablespace being full (might work
> in production, but if it's full during recovery, the whole server will
> stop), I've never seen quotas being used.

I'm +1 on "pg_tablespace_disk_space -> total_bytes | free_bytes"