From: Dmitry Dolgov <9erthalion6@gmail.com>
To: Pavel Stehule <pavel.stehule@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andres Freund <andres@anarazel.de>
Cc: Alexander Korotkov <aekorotkov@gmail.com>
Cc: Justin Pryzby <pryzby@telsasoft.com>
Cc: David Steele <david@pgmasters.net>
Cc: Nikita Glukhov <n.gluhov@postgrespro.ru>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: David Fetter <david@fetter.org>
Cc: Thomas Munro <thomas.munro@gmail.com>
Cc: Oleksandr Shulgin <oleksandr.shulgin@zalando.de>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Michael Paquier <michael.paquier@gmail.com>
Cc: Oleg Bartunov <obartunov@gmail.com>
Cc: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Subject: Re: [HACKERS] [PATCH] Generic type subscripting
Date: Fri, 11 Dec 2020 16:19:57 +0100
Message-ID: <20201211151957.wqlnxdqjwsd7azzd@localhost> (raw)
In-Reply-To: <CAFj8pRCbH_48FfTGHczts8hTA4e0eKhcs5UwdybotoQEH_Pfcg@mail.gmail.com>
References: <20201207212142.wz5tnbk2jsaqzogb@alap3.anarazel.de>
<3253106.1607443505@sss.pgh.pa.us>
<20201209013003.hj4ealuvwmzvczs2@alap3.anarazel.de>
<3459640.1607477907@sss.pgh.pa.us>
<3544235.1607482944@sss.pgh.pa.us>
<3635350.1607536188@sss.pgh.pa.us>
<20201209183704.x5ue5rctdwmhmlmy@localhost>
<3674425.1607540422@sss.pgh.pa.us>
<3724341.1607551174@sss.pgh.pa.us>
<CAFj8pRCbH_48FfTGHczts8hTA4e0eKhcs5UwdybotoQEH_Pfcg@mail.gmail.com>
> On Wed, Dec 09, 2020 at 04:59:34PM -0500, Tom Lane wrote:
>
> 0001 adds the ability to attach a subscript handler to an existing
> data type with ALTER TYPE. This is clearly going to be necessary
> if we want extension types to be able to use this facility. The
> only thing that I think might be controversial here is that I did
> not add the ability to set pg_type.typelem. While that'd be easy
> enough so far as ALTER TYPE is concerned, I'm not sure that we want
> to encourage people to change it. The dependency rules mean that
> the semantics of typelem aren't something you really want to change
> after-the-fact on an existing type. Also, if we did allow it, any
> existing SubscriptingRef.refelemtype values in stored views would
> fail to be updated.
I'm curious what could be the use case for setting pg_type.typelem for
subscripting? I don't see this that much controversial, but maybe I'm
missing something.
> On Thu, Dec 10, 2020 at 05:37:20AM +0100, Pavel Stehule wrote:
> st 9. 12. 2020 v 22:59 odesÃlatel Tom Lane <tgl@sss.pgh.pa.us> napsal:
>
> > 0002 makes use of that to support subscripting of hstore. I'm not
> > sure how much we care about that from a functionality standpoint,
> > but it seems like it might be good to have a contrib module testing
> > that extensions can use this. Also, I thought possibly an example
> > showing what's basically the minimum possible amount of complexity
> > would be good to have. If people like this, I'll finish it up (it
> > lacks docs) and add it.
> >
>
> +1 using subscripts for hstore is nice idea
Yeah, I also find it's a good suggestion, the implementation seems fine
as well. As a side note, I'm surprised hstore doesn't have any
functionality to update values, except hstore_concat.
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To: pgsql-hackers@postgresql.org
Cc: 9erthalion6@gmail.com, pavel.stehule@gmail.com, tgl@sss.pgh.pa.us, andres@anarazel.de, aekorotkov@gmail.com, pryzby@telsasoft.com, david@pgmasters.net, n.gluhov@postgrespro.ru, alvherre@2ndquadrant.com, david@fetter.org, thomas.munro@gmail.com, oleksandr.shulgin@zalando.de, robertmhaas@gmail.com, michael.paquier@gmail.com, obartunov@gmail.com, peter.eisentraut@2ndquadrant.com
Subject: Re: [HACKERS] [PATCH] Generic type subscripting
In-Reply-To: <20201211151957.wqlnxdqjwsd7azzd@localhost>
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