The following bug has been logged on the website:
Bug reference: 16215
Logged by: Stefan Sonnenberg-Carstens
Email address: stefan.sonnenberg.carstens@gmail.com
PostgreSQL version: 10.11
Operating system: Linux
Description:
I tried to restore a binary backup (basebackup + WAL archives) onto a
smaller machine.
During restore the following log message was issued:
2020-01-17 07:14:20.524 UTC [19274] FATAL: hot standby is not possible
because max_worker_processes = 2 is a lower setting than on the master
server (its value was 8)
2020-01-17 07:14:20.526 UTC [19273] LOG: startup process (PID 19274) exited
with exit code 1
2020-01-17 07:14:20.526 UTC [19273] LOG: aborting startup due to startup
process failure
2020-01-17 07:14:20.541 UTC [19273] LOG: database system is shut down
pg_ctl: could not start server
Examine the log output.
The workaround was to raise the number of max_worker_process for the
recovery process to work and lowering it afterwords.
This seems to be a bug to me, as I don't see a technical connection between
these settings for the restore to be successful.
Cheers