Date: Sun, 12 Jul 2020 20:33:10 -0400
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: Masahiko Sawada <masahiko.sawada@2ndquadrant.com>,
	Alexander Korotkov <a.korotkov@postgrespro.ru>,
	Michael Paquier <michael@paquier.xyz>, Tom Lane <tgl@sss.pgh.pa.us>,
	Andres Freund <andres@anarazel.de>,
	Mark Dilger <hornschnorter@gmail.com>,
	pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: WIP: BRIN multi-range indexes
Message-ID: <20200713003310.GA22495@alvherre.pgsql>
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On 2020-Jul-13, Tomas Vondra wrote:

> On Sun, Jul 12, 2020 at 07:58:54PM -0400, Alvaro Herrera wrote:

> > Maybe we can try to handle this with some other function that interprets
> > the bytea in 'value' and returns a user-readable text.  I think it'd
> > have to be a superuser-only function, because otherwise you could easily
> > cause a crash by passing a value of a different opclass.  But since this
> > seems a developer-only thing, that restriction seems fine to me.
> 
> Ummm, I disagree a superuser check is sufficient protection from a
> segfault or similar issues.

My POV there is that it's the user's responsibility to call the right
function; and if they fail to do so, it's their fault.  I agree it's not
ideal, but frankly these pageinspect things are not critical to get 100%
user-friendly.

> If we really want to print something nicer, I'd say it needs to be a
> special function in the BRIN opclass.

If that can be done, then +1.  We just need to ensure that the function
knows and can verify the type of index that the value comes from.  I
guess we can pass the index OID so that it can extract the opclass from
catalogs to verify.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services