On Thu, Aug 27, 2020 at 7:04 AM tsunakawa.ta...@fujitsu.com <tsunakawa.ta...@fujitsu.com> wrote: > > From: Amit Kapila <amit.kapil...@gmail.com> > > So you want your users to shutdown and restart the server before Copy > > because that would be required if you want to change the wal_level. > > Yes. They seem to be fine with it, as far as I heard from a person who is > involved in the system design. > > > > However, even if we do that, users who are running the server > > previously with wal_level as 'replica' won't be happy after doing this > > change. Because if they change the wal_level to 'none' for certain > > operations like bulk load and then again change back the mode to > > 'replica' they need to back up the database again to setup 'replica' > > as they can't continue replication from the previous point (consider > > update on a page for which previously WAL was not written). > > Yes, it requires the database backup. The database backup should be a daily > task anyway, so I expect it wouldn't impose extra maintenance burdon on the > user. >
Sure, but on a daily basis, one requires only incremental WAL to complete the backup but in this case, it would require the entire database back up unless we have some form of block-level incremental backup method. OTOH, I don't deny that there is some use case with wal_level = 'none' for initial data loading as MySQL provides but I think that is a separate feature than what is proposed here (Copy Unlogged). It might be better if you can start a separate thread for that with some more details on the implementation side as well. -- With Regards, Amit Kapila.
