From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
cc: "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: allowing extensions to control planner behavior
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Comments: In-reply-to Robert Haas <robertmhaas@gmail.com>
	message dated "Tue, 27 Aug 2024 13:17:48 -0400"
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Date: Tue, 27 Aug 2024 14:24:50 -0400
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Robert Haas <robertmhaas@gmail.com> writes:
> Well, now I'm confused. Just yesterday, in response to the 0001 patch
> that allows extensions to exert control over the join strategy, you
> complained that "Or, if your problem is that the planner wants to scan
> index A but you want it to scan index B, enable_indexscan won't help."

I was just using that to illustrate that making the enable_XXX GUCs
relation-local covers only a small part of the planner-control problem.
You had not, at that point, been very clear that you intended that
patch as only a small part of a solution.

I do think that index selection is pretty well under control already,
thanks to stuff that we put in ages ago at the urging of people who
wanted to write "index advisor" extensions.  (The fact that that
area seems a bit moribund is disheartening, though.  Is it a lack
of documentation?)

			regards, tom lane