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From: "David G. Johnston" <david.g.johnston@gmail.com>
Date: Wed, 1 Oct 2025 07:38:12 -0500
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 <CAKFQuwbTyugCotCc5dE-5Njy3MG3ZVgDd2c_J9=fU541dnaOWA@mail.gmail.com>
Subject: 
 =?UTF-8?Q?Re=3A_in_the_different_schema_=EF=BC=8Cthe_sequence_name_is_?=
	=?UTF-8?Q?same=EF=BC=8C_and_a_table=27s_column_definition_use_this_sequence=2Cso?=
	=?UTF-8?Q?=EF=BC=8Chow_can_I_identify_sequence=27s_schema_name_by_system_view=2F?=
	=?UTF-8?Q?table=3A?=
To: yanliang lei <msdnchina@163.com>
Cc: "pgsql-docs@lists.postgresql.org" <pgsql-docs@lists.postgresql.org>
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On Wednesday, October 1, 2025, David G. Johnston <david.g.johnston@gmail.co=
m>
wrote:

> On Wednesday, October 1, 2025, yanliang lei <msdnchina@163.com> wrote:
>>
>> dbversion180=3D# create table schema_1.test_tab_100(c1 int default
>> nextval('seq_xx_yy'));
>>
>
> Since you didn=E2=80=99t schema qualify the sequence name every single ti=
me a
> default value is created the sequence will be looked up anew.  The stored
> expression is not associated with any specific object.
>
> This is also why there is a separate step to mark a sequence as being
> owned by a table.  That establishes a dependency that this textual form i=
s
> unable to do.
>
>
 Ignore that=E2=80=A6we do stored the parsed representation which nominally=
 has the
schema recorded, it=E2=80=99s just that the text serialization it too =E2=
=80=9Chelpful=E2=80=9D by
inspecting the search_path and only produces the schema prefix if it would
be necessary to resolve the reference.

David J.

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On Wednesday, October 1, 2025, David G. Johnston &lt;<a href=3D"mailto:davi=
d.g.johnston@gmail.com">david.g.johnston@gmail.com</a>&gt; wrote:<br><block=
quote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc=
 solid;padding-left:1ex">On Wednesday, October 1, 2025, yanliang lei &lt;<a=
 href=3D"mailto:msdnchina@163.com" target=3D"_blank">msdnchina@163.com</a>&=
gt; wrote:<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;bord=
er-left:1px #ccc solid;padding-left:1ex"><div style=3D"line-height:1.7;colo=
r:#000000;font-size:14px;font-family:Arial"><div>dbversion180=3D# create ta=
ble schema_1.test_tab_100(c1 int default  nextval(&#39;seq_xx_yy&#39;));
</div></div></blockquote><div><br></div><div>Since you didn=E2=80=99t schem=
a qualify the sequence name every single time a default value is created th=
e sequence will be looked up anew.=C2=A0 The stored expression is not assoc=
iated with any specific object.</div><div><br></div><div>This is also why t=
here is a separate step to mark a sequence as being owned by a table.=C2=A0=
 That establishes a dependency that this textual form is unable to do.</div=
><div><br></div></blockquote><div>=C2=A0</div><div>=C2=A0Ignore that=E2=80=
=A6we do stored the parsed representation which nominally has the schema re=
corded, it=E2=80=99s just that the text serialization it too =E2=80=9Chelpf=
ul=E2=80=9D by inspecting the search_path and only produces the schema pref=
ix if it would be necessary to resolve the reference.<br></div><div><br></d=
iv><div>David J.</div><div><br></div>

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