Re: Offline enabling/disabling of data checksums

Hi

>> One new question from me: how about replication?
>> Case: primary+replica, we shut down primary and enable checksum, and "started streaming WAL from primary" without any issue. I have master with checksums, but replica without.
>> Or cluster with checksums, then disable checksums on primary, but standby think we have checksums.
>
> Enabling or disabling the checksums offline on the master quite clearly requires a rebuild of the standby, there is no other way (this is one of the reasons for the online enabling in that patch, so I still hope we can get that done -- but not for this version).

I mean this should be at least documented.
Change system id... Maybe is reasonable

>> Also we support ./configure --with-blocksize=(not equals 8)? make check on HEAD fails for me. If we support this - i think we need recheck BLCKSZ between compiled pg_checksum and used in PGDATA
>
> You mean if the backend and pg_checksums is built with different blocksize? Yeah, that sounds like something which is a cheap check and should be done.

Yep