Re: Listen/Notify feedback

One aspect is if there is no one listening when a notify happens, the
message is lost (e.g. no durability). If this is important to you, it can
be addressed by writing the messages to a table as well when you NOTIFY,
and the listener deletes messages after they are processed. On connection
the listener can query the table to catch up on any missed messages, or
messages that were mid-process during a crash. This is trickier with more
than one listener. This isn't a whole lot more efficient than just using
the table alone, but it saves you from having to poll so better response
times.

On Sat, Jul 11, 2020 at 8:58 AM Rita <rmorgan466(at)gmail(dot)com> wrote:

> I am investigating various pub/sub tools such as ActiveMQ, Rabbit, Redis,
> etc.I came across Postgresql Listen/Notify and was easily able to write
> code to listen to messages. For the people who have been using this for a
> while: what are its downsides, things to consider when writing good code
> that use pub/sub, how do you deal with large messages, can I have
> subscribers listen to replica nodes?
>
> Thanks
> --
> --- Get your facts first, then you can distort them as you please.--
>