Hi Shubham, On Mon, Oct 31, 2022 at 11:04 AM Shubham Shingne <shubham.s.shin...@gmail.com> wrote: > > Hi all, > > I am trying to determine optimal standby for automatic failover based on > pg_last_wal_recieve_lsn() value of all slaves. > > But what if max_wal_size is reached, is LSN value reset to zero.
Per https://www.postgresql.org/docs/current/runtime-config-wal.html max_wal_size affects how frequently checkpoints are run. It doesn't specify the limit on WAL produced by a given server. Probably max_wal_size is a misnomer. LSN is never reset to zero AFAIU. > > Please share some documentation that mentions clarification. > > Also suggest if there is any better approach to get node with best RPO out of > all slaves. It depends upon the method used to maintain slaves. Googling "RPO postgresql" provides a lot of links. I found http://www.postgresql-blog.com/postgresql-backup-strategy-recovery-pitr-wal/ to be a good start. But there are many others which seem to be useful too. -- Best Wishes, Ashutosh Bapat
