Server won't start with fallback setting by initdb.

Hello.

I'm not sure such a case happens in the real world nowadays,
initdb uses the fallback value of max_connections=10. But it is
out of favor of server since it is not larger than
max_wal_senders(10).

> postgres: max_wal_senders must be less than max_connections

I think that we can safely increase the fallback value to 20 with
which regtests are known not to fail. I believe that is
preferable than explicitly reducing max_wal_senders in the
generated config file. I confirmed that tegtest won't fail with
the value. (Except with permanent failure of dynamic shared
memory)

I don't find documentation about this behavior.

regards,

--
Kyotaro Horiguchi
NTT Open Source Software Center