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Subject: Re: Lookup tables
From: =?utf-8?Q?Micha=C5=82_K=C5=82eczek?= <michal@kleczek.org>
In-Reply-To: <c77aae45-5914-4973-8d32-9b6efa6545d9@gelassene-pferde.biz>
Date: Wed, 5 Feb 2025 19:13:49 +0100
Cc: pgsql-general@lists.postgresql.org
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Message-Id: <4B983ADC-3A5C-442F-B377-D0C10FC1C100@kleczek.org>
References: <Z6JFgsSGF_kM4yLE@hermes.hilbert.loc>
 <6DCD3899-51A8-4032-A189-F2B51AD7CC8F@kleczek.org>
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To: Thiemo Kellner <thiemo@gelassene-pferde.biz>
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> On 5 Feb 2025, at 19:07, Thiemo Kellner <thiemo@gelassene-pferde.biz> =
wrote:
>=20
> El 04-02-25 a las 18:08, Micha=C5=82 K=C5=82eczek escribi=C3=B3:
>>> Reality tends to become so ambiguous as to not be
>>> reflectable (two entirely different restaurants eventually,
>>> within the flow of time, carry the very same name).
>>>=20
>>> A primary key is very likely not the proper place to reflect
>>> arbitrary business logic (is it the same restaurant or not ?
>>> what if two restaurants have the same name at the same time
>> These are of course problems ( and beyond the scope of my contrived =
example ).
>>=20
>> The point is though, that having surrogate PK not only does not solve =
these issues but makes them worse by kicking the can down the road and =
allowing for inconsistencies.
> Only if you do not see the primary key as the main immutable value =
identifying an object, entity, you name it.

Surrogate key cannot identify any (real) object by definition :)
What object is identified by PK value 42 in =E2=80=9Crestaurants=E2=80=9D =
table?

> Having said that, it is very questionable that a natural key (names to =
name one) can be a suitable primary key (think of typo).

Typos are indeed a problem but adding surrogate key does not solve it, =
I=E2=80=99m afraid.

=E2=80=94
Michal=