On Saturday, March 29, 2025, Robert Treat <r...@xzilla.net> wrote: > On Thu, Mar 27, 2025 at 5:57 PM David G. Johnston > <david.g.johns...@gmail.com> wrote: > > On Thu, Mar 27, 2025 at 2:28 PM Robert Treat <r...@xzilla.net> wrote: > >> On Thu, Mar 27, 2025 at 12:06 PM David G. Johnston > >> <david.g.johns...@gmail.com> wrote: > >> > I expanded upon the material regarding using different file systems > and disks. > >> > > >> > I would like to add a similar "why" to the mount point recommendation > but don't know what that would be. Suggestions welcomed. > >> > > >> > > > > If I mount the filesystem on disk2 to: /mnt/disk2 > > Why do I need to create "/mnt/disk2/wal_files/" and point there instead > of: "/mnt/disk2/"? > > > > eventually came across this from > https://www.postgresql.org/docs/devel/creating-cluster. > html#CREATING-CLUSTER-MOUNT-POINTS > > "Best practice is to create a directory within the mount-point > directory that is owned by the PostgreSQL user, and then create the > data directory within that. This avoids permissions problems,..." > > Which I do remember having tried to do it directly and the OS > complaining that my mount point wasn't owned by root and/or Postgres > complaining that the xlog dir wasn't owned by Postgres, so I think > this advice probably still holds. > > Thank you, I can definitely work that in and it makes sense.
On the topic of verbosity, I found the wording for —pgdata in pg_basebackup to support the more complete description. https://www.postgresql.org/docs/current/app-pgbasebackup.html I believe that at least documenting external side-effects should be required. I’m less convinced that pre-conditions that will be checked by the application need to be listed. But for now I’m going to copy pg_basebackup as my example and at some point might get to doing a survey and proposing a new standard wording for —waldir and —pgdata descriptions regarding creation. The comment regarding absolute paths will remain unwritten. David J.
