On Sun, Feb 25, 2018 at 9:54 AM, Magnus Hagander <mag...@hagander.net> wrote: > Also if that wasn't clear -- we only do the full page write if there isn't > already a checksum on the page and that checksum is correct.
Hmm. Suppose that on the master there is a checksum on the page and that checksum is correct, but on the standby the page contents differ in some way that we don't always WAL-log, like as to hint bits, and there the checksum is incorrect. Then you'll enable checksums when the standby still has some pages without valid checksums, and disaster will ensue. I think this could be hard to prevent if checksums are turned on and off multiple times. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
