On Sun, Mar 29, 2020 at 10:08 PM Andres Freund <andres@anarazel.de> wrote:
> See the attached minimal prototype for what I am thinking of.
>
> This would not correctly handle the case where the timeline changes
> while taking a base backup. But I'm not sure that'd be all that serious
> a limitation for now?
>
> I'd personally not want to use a base backup that included a timeline
> switch...
Interesting concept. I've never (or almost never) used the -s and -e
options to pg_waldump, so I didn't think about using those. I think
having a --just-parse option to pg_waldump is a good idea, though
maybe not with that name e.g. we could call it --quiet.
It is less obvious to me what to do about all that as it pertains to
the current patch. If we want pg_validatebackup to run pg_waldump in
that mode or print out a hint about how to run pg_waldump in that
mode, it would need to obtain the relevant LSNs. I guess that would
require reading the backup_label file. It's not clear to me what we
would do if the backup crosses a timeline switch, assuming that's even
a case pg_basebackup allows. If we don't want to do anything in
pg_validatebackup automatically but just want to document this as a a
possible technique, we could finesse that problem with some
weasel-wording.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
