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References: <19417-401f33ed14f3d4d5@postgresql.org> <CAKFQuwb0SLTxUMUxgE=xegwzwAGXqYJ61McLexszb-vTa4y=Mg@mail.gmail.com>
In-Reply-To: <CAKFQuwb0SLTxUMUxgE=xegwzwAGXqYJ61McLexszb-vTa4y=Mg@mail.gmail.com>
From: yuanchao zhang <zhangyc0706@gmail.com>
Date: Fri, 27 Feb 2026 09:16:56 +0800
Message-ID: <CAADcJZM9rBgPVXQp2WOKx69YvVfoWRPpqRpgFnBxiSX45JACfw@mail.gmail.com>
Subject: Re: BUG #19417: '\dD' fails to list user-defined domains that shadow
 built-in type names (e.g., 'numeric')
To: "David G. Johnston" <david.g.johnston@gmail.com>
Cc: pgsql-bugs@lists.postgresql.org
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Archived-At: <https://www.postgresql.org/message-id/CAADcJZM9rBgPVXQp2WOKx69YvVfoWRPpqRpgFnBxiSX45JACfw%40mail.gmail.com>
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Thank you for your reply.
Okay, I understand the reason you mentioned. However, as a user (especially
a novice user), when they create a domain, they can't directly display
their object. Perhaps the user doesn't understand this internal mechanism
of PostgreSQL. The '\dD' manual states, "By default, only user-created
objects are shown." I think this means that user-created objects will be
displayed. Therefore, when a built-in object appears in the search path
before a user-created object, the user-created object should be displayed.
This is because the user-created object is a domain object, which doesn't
belong to the same type as built-in objects in pg_type (domain type is 'd',
while built-in types use 'b'). Otherwise, it might give the user the
illusion that the object wasn't created successfully. This also applies to
other '\d' commands. Alternatively, we could explicitly explain the object
display mechanism in the command's help documentation, or there are other
ways to avoid this.
Thank you.

Best regards=EF=BC=8C
yuanchao zhang

David G. Johnston <david.g.johnston@gmail.com> =E4=BA=8E2026=E5=B9=B42=E6=
=9C=8827=E6=97=A5=E5=91=A8=E4=BA=94 00:13=E5=86=99=E9=81=93=EF=BC=9A

> On Thu, Feb 26, 2026 at 8:43=E2=80=AFAM PG Bug reporting form <
> noreply@postgresql.org> wrote:
>
>> The following bug has been logged on the website:
>>
>> Bug reference:      19417
>> Logged by:          yuanchao zhang
>> Email address:      zhangyc0706@gmail.com
>> PostgreSQL version: 18.2
>> Operating system:   windows 10
>> Description:
>>
>> Because I checked the documentation regarding the use of '\dD', and ther=
e
>> was no explanation for this special case.
>>
>>
> Because it is not a special case of \dD specifically but a behavior of ho=
w
> all the \d meta-commands function.  This behavior is documented under
> Patterns (here, the absence of specifying any pattern):
>
> ''""
> Whenever the pattern parameter is omitted completely, the \d commands
> display all objects that are visible in the current schema search path =
=E2=80=94
> this is equivalent to using * as the pattern. (An object is said to be
> visible if its containing schema is in the search path and no object of t=
he
> same kind and name appears earlier in the search path. This is equivalent
> to the statement that the object can be referenced by name without explic=
it
> schema qualification.)
> """
>
> Your new domain is not visible since the plain type numeric in pg_catalog
> is implicitly first in the default search_path.
>
> https://www.postgresql.org/docs/current/app-psql.html
>
> https://www.postgresql.org/docs/current/runtime-config-client.html#GUC-SE=
ARCH-PATH
>
> David J.
>
>

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<div dir=3D"ltr"><div>Thank you for your reply.<br>Okay, I understand the r=
eason you mentioned. However, as a user (especially a novice user), when th=
ey create a domain, they can&#39;t directly display their object. Perhaps t=
he user doesn&#39;t understand this internal mechanism of PostgreSQL. The &=
#39;\dD&#39; manual states, &quot;By default, only user-created objects are=
 shown.&quot; I think this means that user-created objects will be displaye=
d. Therefore, when a built-in object appears in the search path before a us=
er-created object, the user-created object should be displayed. This is bec=
ause the user-created object is a domain object, which doesn&#39;t belong t=
o the same type as built-in objects in pg_type (domain type is &#39;d&#39;,=
 while built-in types use &#39;b&#39;). Otherwise, it might give the user t=
he illusion that the object wasn&#39;t created successfully. This also appl=
ies to other &#39;\d&#39; commands. Alternatively, we could explicitly expl=
ain the object display mechanism in the command&#39;s help documentation, o=
r there are other ways to avoid this.<br>Thank you.</div><div><br></div><di=
v>Best regards=EF=BC=8C</div><div>yuanchao zhang</div></div><br><div class=
=3D"gmail_quote gmail_quote_container"><div dir=3D"ltr" class=3D"gmail_attr=
">David G. Johnston &lt;<a href=3D"mailto:david.g.johnston@gmail.com">david=
.g.johnston@gmail.com</a>&gt; =E4=BA=8E2026=E5=B9=B42=E6=9C=8827=E6=97=A5=
=E5=91=A8=E4=BA=94 00:13=E5=86=99=E9=81=93=EF=BC=9A<br></div><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"><div dir=3D"ltr"><div dir=3D"ltr"><div =
class=3D"gmail_default" style=3D"font-family:arial,helvetica,sans-serif"><s=
pan style=3D"font-family:Arial,Helvetica,sans-serif">On Thu, Feb 26, 2026 a=
t 8:43=E2=80=AFAM PG Bug reporting form &lt;<a href=3D"mailto:noreply@postg=
resql.org" target=3D"_blank">noreply@postgresql.org</a>&gt; wrote:</span></=
div></div><div class=3D"gmail_quote"><blockquote class=3D"gmail_quote" styl=
e=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);paddin=
g-left:1ex">The following bug has been logged on the website:<br>
<br>
Bug reference:=C2=A0 =C2=A0 =C2=A0 19417<br>
Logged by:=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 yuanchao zhang<br>
Email address:=C2=A0 =C2=A0 =C2=A0 <a href=3D"mailto:zhangyc0706@gmail.com"=
 target=3D"_blank">zhangyc0706@gmail.com</a><br>
PostgreSQL version: 18.2<br>
Operating system:=C2=A0 =C2=A0windows 10<br>
Description:=C2=A0 =C2=A0 =C2=A0 =C2=A0 <br><br>
Because I checked the documentation regarding the use of &#39;\dD&#39;, and=
 there<br>
was no explanation for this special case.<br><br></blockquote><div><br></di=
v><div class=3D"gmail_default" style=3D"font-family:arial,helvetica,sans-se=
rif">Because it is not a special case of \dD specifically but a behavior of=
 how all the \d meta-commands function.=C2=A0 This behavior is documented u=
nder Patterns (here, the absence of specifying any pattern):</div><div clas=
s=3D"gmail_default" style=3D"font-family:arial,helvetica,sans-serif"><br></=
div><div class=3D"gmail_default" style=3D"font-family:arial,helvetica,sans-=
serif">&#39;&#39;&quot;&quot;</div><div class=3D"gmail_default" style=3D"fo=
nt-family:arial,helvetica,sans-serif">Whenever the pattern parameter is omi=
tted completely, the \d commands display all objects that are visible in th=
e current schema search path =E2=80=94 this is equivalent to using * as the=
 pattern. (An object is said to be visible if its containing schema is in t=
he search path and no object of the same kind and name appears earlier in t=
he search path. This is equivalent to the statement that the object can be =
referenced by name without explicit schema qualification.)</div><div class=
=3D"gmail_default" style=3D"font-family:arial,helvetica,sans-serif">&quot;&=
quot;&quot;</div><div class=3D"gmail_default" style=3D"font-family:arial,he=
lvetica,sans-serif"><br></div><div class=3D"gmail_default" style=3D"font-fa=
mily:arial,helvetica,sans-serif">Your new domain is not visible since the p=
lain type numeric in pg_catalog is implicitly first in the default search_p=
ath.</div><div class=3D"gmail_default" style=3D"font-family:arial,helvetica=
,sans-serif"><br></div><div class=3D"gmail_default" style=3D"font-family:ar=
ial,helvetica,sans-serif"><a href=3D"https://www.postgresql.org/docs/curren=
t/app-psql.html" target=3D"_blank">https://www.postgresql.org/docs/current/=
app-psql.html</a></div><div class=3D"gmail_default" style=3D"font-family:ar=
ial,helvetica,sans-serif"><a href=3D"https://www.postgresql.org/docs/curren=
t/runtime-config-client.html#GUC-SEARCH-PATH" target=3D"_blank">https://www=
.postgresql.org/docs/current/runtime-config-client.html#GUC-SEARCH-PATH</a>=
</div><div class=3D"gmail_default" style=3D"font-family:arial,helvetica,san=
s-serif"><br></div><div class=3D"gmail_default" style=3D"font-family:arial,=
helvetica,sans-serif">David J.</div><div class=3D"gmail_default" style=3D"f=
ont-family:arial,helvetica,sans-serif"><br></div></div></div>
</blockquote></div>

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