Re: BUG #15582: ALTER TABLE/INDEX ... SET TABLESPACE does not free disk space

On Thu, Jan 10, 2019 at 07:22:00PM +1100, AP wrote:
> > > I suspect the issue is that we don't properly close the old relation in
> > > all backends that had it open, but it's hard to know for sure without
> > > that. If restarting isn't feasible, ensuring all backends older than
> > > the move are ended, and issuing a CHECKPOINT; might also free the space
> > > after a few seconds.
> >
> > I did a CHECKPOINT (it was fast) and it did not help. Then I did a restart
> > and space is still used.
>
> I tried it again (because I need to write data to the db ASAP) with other
> tables that are actively being written to (the previous lot were "archived"
> tables) and I noticed this in the logs:
>
> ERROR: [082]: unable to push WAL segment '00000001000117BB00000001' asynchronously after 60 second(s)
> 2019-01-10 19:06:25.753 AEDT [21662] LOG: archive command failed with exit code 82
> 2019-01-10 19:06:25.753 AEDT [21662] DETAIL: The failed archive command was: pgbackrest --stanza=zonk archive-push pg_wal/00000001000117BB00000001

So I restarted this ALTER to the new tablespace and let it complete. This time
it freed disk space on the source (the above errors kept happening, though).

The original 5.5TB, though, is still duplicated and now I've a DB bigger than
the original storage can contain. :(

AP