On 10/27/23 13:34, Paul Förster wrote:
Hi, I have a few questions about pg_checksums. Long story short, checksums were disabled in our environment but are getting enabled now (again!) because of block corruptions which destroyed a few databases in a database cluster. And before you say "told you so", the decision to disable checksums was not mine. Some people just have to learn the hard way. Anyway, re-enabling data checksums creates a few questions: a) why isn't it possible to enable checksumming while a database cluster is up?
Data might be changing.
b) why isn't it possible to check whether checksums are enabled or not?
(This is my tiny test instance.) $ pg_controldata | grep checksum Data page checksum version: 0 postgres=# show data_checksums; data_checksums ---------------- off (1 row)
c) in a Patroni cluster consisting of a primary and a sync standby, is it safe to enable checksumming in the replica, then switch over and enable it in the ex-primary, i.e. now new replica, without any penalty? Or do I have to perform a reinit to really get them in sync again, though paronictl happily reports them to be in sync? d) how long does it take to enable checksums in general? Minimizing down-time is crucial. Does it depend on the database cluster size, or the number of files it uses, or what can be taken as a criterion to estimate then necessary down-time. Thanks in advance for your insights. Cheers Paul
-- Born in Arizona, moved to Babylonia.
