Re: [PATCH] Support % wildcard in extension upgrade filenames

On Mon, Apr 24, 2023 at 01:06:24PM -0400, Mat Arye wrote:
> Hi All,
>
> I've done upgrade maintenance for multiple extensions now (TimescaleDB
> core, Promscale) and I think the original suggestion (wildcard filenames
> with control-file switch to enable) here is a good one.

Thanks for your comment, Mat.

I'm happy to bring back the control-file switch if there's an
agreement about that.

The rationale for me to add that was solely to be 100% sure about not
breaking any extension using "%" character as an actual version.

I never considered it a security measure because the author of the control
file is the same as the author of the ugprade scripts so shipping a
wildcard upgrade script could be seen as a switch itself.

[...]

> As for Tom's concern about downgrades, I think it's valid but it's a case
> that is easy to test for in Plpgsql and either handle or error. For
> example, we use semver so testing for a downgrade at the top of the upgrade
> script is trivial.

I'd say it could be made even easier if PostgreSQL itself would provide
a variable (or other way to fetch it) for the "source" version of the extension
during exection of the "source"--"target" upgrade.

I'm saying this because PostGIS fetches this version by calling a
PostGIS function, but some extensions might have such "version"
function pointing to a C file that doesn't exist enymore at the time
of upgrade and thus would be left with the impossibility to rely on
calling it.

--strk;