From: Dian M Fay <dian.m.fay@gmail.com>
To: Dmitry Dolgov <9erthalion6@gmail.com>
Cc: 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: Wed, 20 Jan 2021 11:34:16 -0500
Message-ID: <C8O4PRM04CWJ.204R7D05JOJLB@lamia> (raw)
In-Reply-To: <20210120162231.4oht6mdp6v76xfhs@localhost>
On Wed Jan 20, 2021 at 11:22 AM EST, Dmitry Dolgov wrote:
> > On Tue Jan 19, 2021 at 1:42 PM EST, Pavel Stehule wrote:
> >
> > I found minor issues.
> >
> > Doc - missing tag
> >
> > and three whitespaces issues
> >
> > see attached patch
>
> Thanks, I need to remember to not skipp doc building for testing process
> even for such small changes. Hope now I didn't forget anything.
>
> > On Wed, Jan 20, 2021 at 09:58:43AM -0500, Dian M Fay wrote:
>
> > Here's a full editing pass on the documentation, with v45 and Pavel's
> > doc-whitespaces-fix.patch applied. I also corrected a typo in one of the
> > added hints.
>
> Great! I've applied almost all of it, except:
>
> + A <type>jsonb</type> value will accept assignments to nonexistent
> subscript
> + paths as long as the nonexistent elements being traversed are all
> arrays.
>
> Maybe I've misunderstood the intention, but there is no requirement
> about arrays for creating such an empty path. I've formulated it as:
>
> + A <type>jsonb</type> value will accept assignments to nonexistent
> subscript
> + paths as long as the last existing path key is an object or an array.
My intention there was to highlight the difference between:
* SET obj['a']['b']['c'] = '"newvalue"'
* SET arr[0][0][3] = '"newvalue"'
obj has to conform to {"a": {"b": {...}}} in order to receive the
assignment of the nested c. If it doesn't, that's the error case we
discussed earlier. But arr can be null, [], and so on, and any missing
structure [[[null, null, null, "newvalue"]]] will be created. Take 2:
A <type>jsonb</type> value will accept assignments to nonexistent
subscript paths as long as object key subscripts can be traversed as
described above. The final subscript is not traversed and, if it
describes a missing object key, will be created. Nested arrays will
always be created and <literal>NULL</literal>-padded according to the
path until the value can be placed appropriately.
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To: pgsql-hackers@postgresql.org
Cc: dian.m.fay@gmail.com, 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: <C8O4PRM04CWJ.204R7D05JOJLB@lamia>
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