Re: Proposal: Progressive explain

On Fri, Mar 28, 2025 at 12:09 PM Rafael Thofehrn Castro
<rafaelthca(at)gmail(dot)com> wrote:
> I am definitely not the authority here to talk about the best way forward.
> If there is an agreement in turning this into an extension, it can be a new
> feature in auto_explain.

I'm not against adding some more hooks to explain.c, but I don't
really see how you could add hooks to explain.c that would allow
somebody to implement this feature out of core, unless either (a) you
are thinking that they will copy and paste a lot of core code or (b)
you make the hooks extremely fine-grained and special-purpose,
designed to accomplish the extremely precise thing that this feature
would need them to do. But that just seems like bad hook design. I
don't think hooks have to be amazingly general in order to be
accepted, but if there's no use of the hook that doesn't involve a big
cut-and-paste operation, that's poor, and if the hook can only ever be
used to implement one thing, you might as well put the thing in core.

I feel like there are just two separate things here. There is Rafael's
progressive EXPLAIN patch which, as far as I can see currently, is
really only going to work as in-core feature, and then there is
Andrei's desire for more hooks, which may very well also be a good
idea but not the same idea.

--
Robert Haas
EDB: http://www.enterprisedb.com