From: Tom Lane <tgl@sss.pgh.pa.us>
To: Ed Sabol <edwardjsabol@gmail.com>
cc: Pgsql-admin <pgsql-admin@lists.postgresql.org>
Subject: Re: Duplicate key value violates unique constraint
 "pg_type_typname_nsp_index" error
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References: <1D3D88D6-5E8C-4144-BF79-DB531FE4FE39@gmail.com>
Comments: In-reply-to Ed Sabol <edwardjsabol@gmail.com>
	message dated "Wed, 18 Feb 2026 20:47:27 -0500"
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Date: Wed, 18 Feb 2026 23:51:57 -0500
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Ed Sabol <edwardjsabol@gmail.com> writes:
> Using PostgreSQL 15.16, I have some SQL for creating a materialized view=
 that's inside a larger transaction which randomly emits the following err=
or:
> ERROR:  duplicate key value violates unique constraint "pg_type_typname_=
nsp_index"
> DETAIL:  Key (typname, typnamespace)=3D(largetable, 20488) already exist=
s.

Huh.  Does it always mention 20488?

> I've tried the following queries to try to figure out what typnamespace =
=3D 20488 refers to:

> SELECT nspname FROM pg_namespace WHERE oid =3D 20488;
> SELECT count(*) FROM pg_catalog.pg_type WHERE typname =3D 'targetable' A=
ND typnamespace =3D 20488;

> Neither query provides any useful information.

What do you mean by "any useful information", exactly?  Do these show
that there is no pg_namespace row with oid =3D 20488?

If that is the case, I'd bet on index corruption in the indexes of
pg_type and/or pg_namespace.  REINDEX might help.

			regards, tom lane