Re: Why is hot_standby_feedback off by default?

Agreed. I believe that any reasonable use of a standby server for queries requires hot_standby_feedback to be turned on. Otherwise, we can potentially see query cancellations, increased replication lag because of conflicts (while replaying vacuum cleanup records) on standby (resulting in longer failover times if the server is configured for disaster recovery + read scaling). Recent logical decoding on standby as well requires hot_standby_feedback to be turned on to avoid slot invalidation [1]. If there is no requirement to query the standby, admins can always  set hot_standby to off. My goal here is to minimize the amount of configuration tuning required to use these features.

[1]: https://www.postgresql.org/docs/current/logicaldecoding-explanation.html

Thanks,

Sirisha