Re: Extensibility of the PostgreSQL wire protocol

On Wed, Feb 10, 2021 at 11:43 AM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> On Mon, Jan 25, 2021 at 10:07 AM Jan Wieck <jan(at)wi3ck(dot)info> wrote:
> > Our current plan is to create a new set of API calls and hooks that
> allow to register additional wire protocols. The existing backend libpq
> implementation will be modified to register itself using the new API. This
> will serve as a proof of concept as well as ensure that the API definition
> is not slanted towards a specific protocol. It is also similar to the way
> table access methods and compression methods are added.
>
> If we're going to end up with an open source implementation of
> something useful in contrib or whatever, then I think this is fine.
> But, if not, then we're just making it easier for Amazon to do
> proprietary stuff without getting any benefit for the open-source
> project. In fact, in that case PostgreSQL would ensure have to somehow
> ensure that the hooks don't get broken without having any code that
> actually uses them, so not only would the project get no benefit, but
> it would actually incur a small tax. I wouldn't say that's an
> absolutely show-stopper, but it definitely isn't my first choice.
>

Agreed on adding substantial hooks if they're not likely to be used. While
I haven't yet seen AWS' implementation or concrete proposal, given the
people involved, I assume it's fairly similar to how I implemented it.
Assuming that's correct and it doesn't require substantial redevelopment,
I'd certainly open-source my MySQL-compatible protocol and parser
implementation. From my perspective, it would be awesome if these could be
done as extensions.

While I'm not planning to open source it as of yet, for my
Oracle-compatible stuff, I don't think I'd be able to do anything other
than the protocol as an extension given the core-related changes similar to
what EDB has to do. I don't think there's any easy way to get around that.
But, for the protocol and any type of simple translation to Postgres'
dialect, I think that could easily be hook-based.

--
Jonah H. Harris