On Tue, Mar 27, 2018 at 10:06 PM, Michael Paquier <mich...@paquier.xyz> wrote: > On Tue, Mar 27, 2018 at 02:02:10PM -0400, Tom Lane wrote: >> Robert Haas <robertmh...@gmail.com> writes: >>> On Tue, Mar 27, 2018 at 11:41 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: >>>> This is ignoring the possibility of damaged data in between, ie >>>> A ... B ... CHKPT ... C ... a few zeroed pages ... D ... CHKPT ... E ... F >> >>> It's hard for me to believe that this case matters very much. If >>> you're trying to run pg_rewind on a system where the WAL segments >>> contain a few zeroed pages, you're probably going to be hosed anyway, >>> if not by this particular thing then by something else. >> >> Well, the point of checkpoints is that WAL data before the last one >> should no longer matter anymore, isn't it? > > I have to agree with Tom here. If you force pg_rewind to replay more > WAL records from a checkpoint older than the checkpoint prior to where > WAL has forked at promotion then you have a risk of losing data.
Oh! I see now. Good point. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
