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: > > > > Version 2 Attached > > > > - This option specifies the directory where the write-ahead log > > - should be stored. > > + This option specifies the directory in which to store > write-ahead log files. > > + See <xref linkend="wal-internals-relocation"/> for more > information. > > To be honest, I think the proposed text is a little verbose, and we > could cut it right here. As an example, we don't go into how the > directory must be empty or chnmod settings for --pgdata. I'd also edit > the pg_basebackup changes to match if it were me. > Don't really see how completeness hurts here, but also not married to it. > > > + the <option>--waldir</option> option. On an existing, but not > running, > > + cluster use operating system commands to move the contents of the > > + <filename>pg_wal</filename> directory to the new location, remove the > > + empty directory, and create the symbolic link named > <filename>pg_wal</filename> > > + pointing to the new location. > > I found this to be awkward to read, and not as significant a warning > as the existing text... perhaps "For an existing cluster, once the > cluster has been shut down, you can use operating system commands... " > I'll probably put it back into parentheses to get the desired emphasis. That did nag at me too as I wrote it. > > There being two places now (plus doing it manually) I decided to write > this material in the WAL chapter as opposed to application-specific Notes. > A new section seemed warranted. > > > > +1 > > > 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. > > > > I'm not sure I follow what you are asking for... but a non-performance > reason to use a seperate mount point for pg_wal, even if the > underlying storage is the same, would be for something like using > filesystem snapshots to grab contents of the data directory without > grabbing wal (which can be handled separately). > > 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/"? David J.
