On Tuesday, March 9, 2021 11:13 PM David Steele <da...@pgmasters.net> > On 3/7/21 9:45 PM, osumi.takami...@fujitsu.com wrote: > > On Sun, Mar 7, 2021 3:48 AM Peter Eisentraut > <peter.eisentr...@enterprisedb.com> wrote: > >> On 28.01.21 01:44, osumi.takami...@fujitsu.com wrote: > >>>> (1) writing the time or LSN in the control file to indicate > >>>> when/where wal_level is changed to 'minimal' > >>>> from upper level to invalidate the old backups or make alerts to users. > >>> I attached the first patch which implementes this idea. > >>> It was aligned by pgindent and shows no regression. > >> > >> It's not clear to me what this is supposed to accomplish. I read the > >> thread, but it's still not clear. > >> What is one supposed to do with this information? > > OK. The basic idea is to enable backup management tools to recognize > > wal_level drop between *snapshots*. > > When you have a snapshot of the cluster at one time and another one at > > different time, with this new parameter, you can see if anything that > > causes discontinuity from the drop happens in the middle of the two > > snapshots without efforts to have a look at the WALs in between. > > As a backup software author, I don't see this feature as very useful. > > The problem is that there are lots of ways for WAL to go missing so > monitoring the WAL archive for gaps is essential and this feature would not > replace that requirement. The only extra information you'd get is the ability > to > classify the most recent gap as "intentional", maybe. > > So, -1 from me. Thanks for giving me a meaningful viewpoint. Let me sleep on it, about whether the new param doesn't help in all cases or not.
Best Regards, Takamichi Osumi