From: Tom Lane <tgl@sss.pgh.pa.us>
To: umuttechin@gmail.com
cc: pgsql-docs@lists.postgresql.org
Subject: Re: Modifying Arrays
In-reply-to: <167750600710.23480.2189471451420785675@wrigleys.postgresql.org>
References: <167750600710.23480.2189471451420785675@wrigleys.postgresql.org>
Comments: In-reply-to PG Doc comments form <noreply@postgresql.org>
	message dated "Mon, 27 Feb 2023 13:53:27 +0000"
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Date: Mon, 27 Feb 2023 10:41:06 -0500
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PG Doc comments form <noreply@postgresql.org> writes:
> According to the official document of PostgreSQL 15, in the section 8.15=
.4.
> Modifying Arrays there is a statement like:

> The slice syntaxes with omitted lower-bound and/or upper-bound can be us=
ed
> too, but only when updating an array value that is not NULL or
> zero-dimensional (otherwise, there is no existing subscript limit to
> substitute).

> This statement is not true for the following statements or I am missing
> something?

Your example doesn't use a slice with omitted bound, so I'm not quite sure
what you are trying to show?  Using your test data, a slice with omitted
bound does fail with Pam's null schedule:

=3D> UPDATE sal_emp SET schedule[:2] =3D '{"w", "x", "y", "z"}' WHERE name=
 =3D 'Pam';
ERROR:  array slice subscript must provide both boundaries
DETAIL:  When assigning to a slice of an empty array value, slice boundari=
es must be fully specified.

but it works for the other entries:

=3D> UPDATE sal_emp SET schedule[:2] =3D '{"w", "x", "y", "z"}' WHERE name=
 !=3D 'Pam';
UPDATE 3
=3D> table sal_emp;
  name  |      pay_by_quarter       |            schedule             =

--------+---------------------------+---------------------------------
 Pam    | {20000,25001,25002,25003} | =

 Bill   | {10000,10000,10000,10000} | {{w,x},{y,z}}
 Carol  | {20000,25000,25000,25000} | {{w,x},{y,z}}
 Carolx | {20000,25001,25002,25003} | {{w,x},{y,z},{meetingy,lunchy}}
(4 rows)

			regards, tom lane