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help / color / mirror / Atom feedFrom: Tom Lane <tgl@sss.pgh.pa.us>
To: David G. Johnston <david.g.johnston@gmail.com>
Cc: "Сергей П (SergeiDos)" <podrezov.sergey@gmail.com>
Cc: pgsql-docs@lists.postgresql.org <pgsql-docs@lists.postgresql.org>
Subject: Re: Generated names (suffix) for constraints not described in docs
Date: Wed, 13 Nov 2024 10:00:50 -0500
Message-ID: <1363392.1731510050@sss.pgh.pa.us> (raw)
In-Reply-To: <CAKFQuwYypoe_44QXqXokL0rq8j-Kbv52fynTG2nFPnb4kjjmJQ@mail.gmail.com>
References: <712E40A2-744F-424E-AE45-95CE5BE27D82@gmail.com>
<CAKFQuwYypoe_44QXqXokL0rq8j-Kbv52fynTG2nFPnb4kjjmJQ@mail.gmail.com>
"David G. Johnston" <david.g.johnston@gmail.com> writes:
> On Wednesday, November 13, 2024, "Сергей П (SergeiDos)" <
> podrezov.sergey@gmail.com> wrote:
>> In the documentation for the Constraints section
>> https://www.postgresql.org/docs/current/ddl-constraints.html there is a
>> phrase: "So, to specify a named constraint, use the key word CONSTRAINT
>> followed by an identifier followed by the constraint definition. (If you
>> can't specify a constraint name in this way, the system choose a name for
>> you.)"
>> But nowhere in the documentation are the rules by which it generates names
>> on its own described.
> Correct. Which means the specific name chosen is an implementation detail
> that can change at any time and should not be relied upon by the
> DBA.
Indeed. I double-checked the SQL spec and found that it says
3) If <constraint name definition> is not specified, then a
<constraint name definition> that contains an implementation-
dependent <constraint name> is implicit. The assigned
<constraint name> shall obey the Syntax Rules of an explicit
<constraint name>.
"Implementation-dependent" is standards-ese for "implementations
don't have to document their exact behavior". (If it said
"implementation-defined", that would mean we should.) So not
documenting it is expected. I think we have indeed changed the
details around this in the past.
regards, tom lane
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Cc: tgl@sss.pgh.pa.us, david.g.johnston@gmail.com, podrezov.sergey@gmail.com, pgsql-docs@lists.postgresql.org
Subject: Re: Generated names (suffix) for constraints not described in docs
In-Reply-To: <1363392.1731510050@sss.pgh.pa.us>
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