Re: BackendKeyData is mandatory?

>>> Do we know which implementations aren't sending keys?
> 
>> Nope, that's totally unclear. It would be very nice knowing which
>> database this is, and if it's at all a production system.
> 
> Yeah, I'm very hesitant to spend any effort here without having
> a more concrete use-case.

One example is Amazon RDS Proxy.
https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/rds-proxy.html

See the section:
"Additional limitations for RDS for PostgreSQL"

I haven't tried Amazon RDS Proxy myself but I heard about it in a
conversation with a Pgpool-II user. He tried to use Pgpool-II with
Amazon RDS Proxy and failed.

https://github.com/pgpool/pgpool2/issues/111

Best regards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp