Re: Built-in plugin for logical decoding output

On 26/09/17 10:55, Craig Ringer wrote:
> On 26 September 2017 at 15:26, Alvaro Hernandez <aht(at)ongres(dot)com
> <mailto:aht(at)ongres(dot)com>> wrote:
>
>
>     That's better than nothing. But as much as interoperable json
> may be, people still need to talk the (binary) replication
> protocol to use it.
>
>
> No, they don't.
>
> They can use the SQL interface to logical decoding.

    AFAIK the SQL interface was also designed for testing, not for
production use...

>
> We could enhance that with a few small changes to make it a lot more
> useful too. Most importantly, allow a long-polling model, where you
> can wait if there's nothing to consume rather than getting an
> immediate empty result-set.

    Oh, that's a completely different perspective! Do we have any
support for long-polling style queries (not that I know of). It's indeed
a cool thing: SQL queries that return "live" results as soon as they
happen. I don't see this restricted to logical decoding. Actually, this
is what PipelineDB, among other things, seem to do. +1 for that, but I
believe it's a different story.

>
> I expect the walsender protocol to be dealt with by client drivers,
> not user applications, much like you never really deal with the
> regular libpq protocol in your app. PgJDBC and psycopg2 already
> support it. It'd be nice if libpq offered some helper interfaces for C
> apps, and I'd help review any such patch.

    Fair enough.

    Álvaro

--

Alvaro Hernandez

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