Re: Built-in plugin for logical decoding output

On 24 September 2017 at 07:41, Euler Taveira <euler(at)timbira(dot)com(dot)br> wrote:

> It is difficult to
> coordinate a change like that having only one-way communication).
> <http://www.postgresql.org/mailpref/pgsql-hackers>
>

I really think we need to fix that at some point, such that:

* Downstream connections can send CopyData messages *up* the COPY BOTH
protocol, where they're passed to a hook on the output plugin; and

* Output plugins can hook the walsender's event loop (latch set, etc) and
send their own messages without being driven by a logical decoding event .

I wanted to do that some time ago but ran into some issues and time
constraints. Because of the need to support older versions I'm now
committed to an approach using direct libpq connections and function calls
instead, but it seems like a real shame to do that when the replication
protocol connection is *right there*...

--
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services