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From: Ron Johnson <ronljohnsonjr@gmail.com>
Date: Tue, 15 Apr 2025 17:17:57 -0400
Message-ID: <CANzqJaA=cVJz7NKdAVMKXMnKYvmeD_+AHvc0c+mQDwCa-tM7tg@mail.gmail.com>
Subject: Re: Fwd: Identify system databases
To: "pgsql-generallists.postgresql.org" <pgsql-general@lists.postgresql.org>
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On Tue, Apr 15, 2025 at 3:11=E2=80=AFPM Tom Lane <tgl@sss.pgh.pa.us> wrote:

> "David G. Johnston" <david.g.johnston@gmail.com> writes:
> > On Tue, Apr 15, 2025 at 11:20=E2=80=AFAM Adrian Klaver <
> adrian.klaver@aklaver.com>
> > wrote:
> >> If what you say is true why does initdb lack an option to not create
> >> them on creating a cluster?
>
> > By creating the initial three databases the system is more usable due t=
o
> > having established conventions.  They are conventional databases, not
> > system ones.
>
> Precisely.  For example, the only reason for the "postgres" database
> to exist is so that there is a reasonable default database for clients
> to connect to.  If we didn't have it we'd need some other convention.
> (Indeed, we used to not have it, and back then the default client
> behavior was usually to connect to template1.  That led to people
> creating random junk in template1 and then being surprised when
> CREATE DATABASE copied it into new databases.)
>

Interesting history.  I've always interpreted the "postgres" database as
being the system database, but now I know it's not.

--=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, Apr 15, 2025 at 3:11=E2=80=AFPM T=
om Lane &lt;<a href=3D"mailto:tgl@sss.pgh.pa.us">tgl@sss.pgh.pa.us</a>&gt; =
wrote:</div><div class=3D"gmail_quote gmail_quote_container"><blockquote cl=
ass=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid=
 rgb(204,204,204);padding-left:1ex">&quot;David G. Johnston&quot; &lt;<a hr=
ef=3D"mailto:david.g.johnston@gmail.com" target=3D"_blank">david.g.johnston=
@gmail.com</a>&gt; writes:<br>
&gt; On Tue, Apr 15, 2025 at 11:20=E2=80=AFAM Adrian Klaver &lt;<a href=3D"=
mailto:adrian.klaver@aklaver.com" target=3D"_blank">adrian.klaver@aklaver.c=
om</a>&gt;<br>
&gt; wrote:<br>
&gt;&gt; If what you say is true why does initdb lack an option to not crea=
te<br>
&gt;&gt; them on creating a cluster?<br>
<br>
&gt; By creating the initial three databases the system is more usable due =
to<br>
&gt; having established conventions.=C2=A0 They are conventional databases,=
 not<br>
&gt; system ones.<br>
<br>
Precisely.=C2=A0 For example, the only reason for the &quot;postgres&quot; =
database<br>
to exist is so that there is a reasonable default database for clients<br>
to connect to.=C2=A0 If we didn&#39;t have it we&#39;d need some other conv=
ention.<br>
(Indeed, we used to not have it, and back then the default client<br>
behavior was usually to connect to template1.=C2=A0 That led to people<br>
creating random junk in template1 and then being surprised when<br>
CREATE DATABASE copied it into new databases.)<br></blockquote><div>=C2=A0<=
/div><div>Interesting history.=C2=A0 I&#39;ve always interpreted the &quot;=
postgres&quot; database as being the system database, but now I know it&#39=
;s not.</div></div><div><br></div><span class=3D"gmail_signature_prefix">--=
 </span><br><div dir=3D"ltr" class=3D"gmail_signature"><div dir=3D"ltr">Dea=
th to &lt;Redacted&gt;, and butter sauce.<div>Don&#39;t boil me, I&#39;m st=
ill alive.<br><div><div>&lt;Redacted&gt; lobster!</div></div></div></div></=
div></div>

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