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From: Ron Johnson <ronljohnsonjr@gmail.com>
Date: Tue, 4 Feb 2025 12:10:03 -0500
Message-ID: <CANzqJaCzhHob2s8tfTamwRBWoSZ+KiAcGZB9+k5618jYxLv1XA@mail.gmail.com>
Subject: Re: Lookup tables
To: "pgsql-generallists.postgresql.org" <pgsql-general@lists.postgresql.org>
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On Tue, Feb 4, 2025 at 12:05=E2=80=AFPM Rob Sargent <robjsargent@gmail.com>=
 wrote:

>
>
>
> On 2/4/25 10:03, Ron Johnson wrote:
>
> On Tue, Feb 4, 2025 at 11:31=E2=80=AFAM Micha=C5=82 K=C5=82eczek <michal@=
kleczek.org> wrote:
> [snip]
>
>>
>> The query to register a visit is:
>> insert into restaurant_visit
>> select $user, current_date, restaurant_id, $rating
>> from restaurant where name =3D $restaurant_name
>>
>>
>> It is now completely unclear what it means to change the name of the
>> restaurant for already registered visits.
>> Is it still the same restaurant with a different name or a different
>> restaurant?
>>
>> Or let say someone swaps names of two restaurants.
>> That means a user that goes to the same restaurant every day would
>> register visits to two different restaurants!
>>
>
> Valid concerns, which means that you add a new restaurant record when the
> name changes.
>
> And there goes your unique index on phone number :)
>

I don't think I'd ever do that, since phone numbers can get reassigned.

Capital-L Large and old businesses probably don't even have unique indices
on SSN.

--=20
Death to <Redacted>, and butter sauce.
Don't boil me, I'm still alive.
<Redacted> lobster!

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<div dir=3D"ltr"><div dir=3D"ltr">On Tue, Feb 4, 2025 at 12:05=E2=80=AFPM R=
ob Sargent &lt;<a href=3D"mailto:robjsargent@gmail.com">robjsargent@gmail.c=
om</a>&gt; wrote:</div><div class=3D"gmail_quote gmail_quote_container"><bl=
ockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-lef=
t:1px solid rgb(204,204,204);padding-left:1ex"><u></u>

 =20
   =20
 =20
  <div>
    <br>
    <br>
    <br>
    <div>On 2/4/25 10:03, Ron Johnson wrote:<br>
    </div>
    <blockquote type=3D"cite">
     =20
      <div dir=3D"ltr">
        <div dir=3D"ltr">On Tue, Feb 4, 2025 at 11:31=E2=80=AFAM Micha=C5=
=82 K=C5=82eczek
          &lt;<a href=3D"mailto:michal@kleczek.org" target=3D"_blank">micha=
l@kleczek.org</a>&gt;
          wrote:</div>
        <div class=3D"gmail_quote">
          <div>[snip]=C2=A0</div>
          <blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8=
ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
            <br>
            The query to register a visit is:<br>
            insert into restaurant_visit<br>
            select $user, current_date, restaurant_id, $rating<br>
            from restaurant where name =3D $restaurant_name<br>
            <br>
            <br>
            It is now completely unclear what it means to change the
            name of the restaurant for already registered visits.<br>
            Is it still the same restaurant with a different name or a
            different restaurant?<br>
            <br>
            Or let say someone swaps names of two restaurants.<br>
            That means a user that goes to the same restaurant every day
            would register visits to two different restaurants!<br>
          </blockquote>
        </div>
        <div><br>
        </div>
        <div>Valid concerns, which means that you add a new restaurant
          record when the name changes.</div></div></blockquote>
    And there goes your unique index on phone number :)<br>
  </div>

</blockquote></div><div><br clear=3D"all"></div><div>I don&#39;t think I=
9;d ever do that, since phone numbers can get reassigned.</div><div><br></d=
iv><div>Capital-L Large and old businesses probably don&#39;t even have uni=
que indices on SSN.</div><div><br></div><span class=3D"gmail_signature_pref=
ix">-- </span><br><div dir=3D"ltr" class=3D"gmail_signature"><div dir=3D"lt=
r">Death to &lt;Redacted&gt;, and butter sauce.<div>Don&#39;t boil me, I=
9;m still alive.<br><div><div>&lt;Redacted&gt; lobster!</div></div></div></=
div></div></div>

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