On Sat, Jul 5, 2025 at 3:19 PM Pierre Fortin <pf@pfortin.com> wrote:
On Sat, 05 Jul 2025 14:30:20 -0400 Tom Lane wrote:
Forgive my ignorance; always trying to learn more... :)
>pf@pfortin.com writes: >> On Sat, 5 Jul 2025 11:11:32 -0700 Adrian Klaver wrote: >>> How did you measure above? > >> # du -sb /var/lib/pgsql/data >> 8227910662297 /var/lib/pgsql/data > >It's likely that there's a deal of bloat in that. Even if there's not >much bloat, this number will include indexes and WAL data that don't >appear in pg_dump output.
Does this imply that on restore, I'll have to re-index everything?
>>> What was the pg_dump command? > >> Didn't try given: >> $ df /mnt/db >> Filesystem Size Used Avail Use% Mounted on >> /dev/sdh1 17T 13T 3.0T 82% /mnt/db > >I'd say give it a try; be sure to use one of the pg_dump modes >that compress the data.
OK... I failed to mention I have several databases in this cluster; so digging into pg_dumpall, I see: --binary-upgrade This option is for use by in-place upgrade utilities. Its use for other purposes is not recommended or supported. The behavior of the option may change in future releases without notice.
pg_upgrade has --link option; but I'm puzzled by this option in a dumpall/restore process.
- pg_dump --format=directory / pg_restore --format=directory of db1
- pg_dump --format=directory / pg_restore --format=directory of db2
- pg_dump --format=directory / pg_restore --format=directory of db3
- pg_dump --format=directory / pg_restore --format=directory of etc...
Why not a plain pg_dumpall of the whole instance? Because that would create a GINORMOUS text file which can only be loaded in a single-threaded manner.
My imagination wonders if this alludes to a way to do something like: pg_dumpall --globals-only --roles-only --schema-only ... Would restoring this be a way to update only the control structures? Big assumption that the actual data remains untouched...
Inquiring mind... :)
Back to my upgrade issue... All my DBs are static (only queries once loaded). Assuming the dumpall file fits on one of my drives: pg_dumpall -f <path>/PG.backup -v appears to be all I need? pg_dump has compression by default; but I don't see compression with dumpall other than for TOAST.
