Message-ID: <d233117a82774de6e606cb383d1e0efea72c8879.camel@j-davis.com>
Subject: Re: [17] CREATE SUBSCRIPTION ... SERVER
From: Jeff Davis <pgsql@j-davis.com>
To: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Cc: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, Joe Conway
	 <mail@joeconway.com>, pgsql-hackers@postgresql.org
Date: Tue, 30 Jan 2024 12:45:39 -0800
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On Tue, 2024-01-30 at 16:17 +0530, Ashutosh Bapat wrote:
> Converting a server and user mapping to
> conninfo should be delegated to the FDW being used since that FDW
> knows best how to use those options.

If I understand you correctly, you mean that there would be a new
optional function associated with an FDW (in addition to the HANDLER
and VALIDATOR) like "CONNECTION", which would be able to return the
conninfo from a server using that FDW. Is that right?

I like the idea -- it further decouples the logic from the core server.
I suspect it will make postgres_fdw the primary way (though not the
only possible way) to use this feature. There would be little need to
create a new builtin FDW to make this work.

To get the subscription invalidation right, we'd need to make the
(reasonable) assumption that the connection information is based only
on the FDW, server, and user mapping. A FDW wouldn't be able to use,
for example, some kind of configuration table or GUC to control how the
connection string gets created. That's easy enough to solve with
documentation.

I'll work up a new patch for this.


Regards,
	Jeff Davis