From: Laurenz Albe <laurenz.albe@cybertec.at>
To: 409800246@qq.com
To: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18173: ERROR: could not identify a comparison function for type unknown
Date: Tue, 31 Oct 2023 12:10:05 +0100
Message-ID: <52e52bddd9d5396ca07f103f799518f82e2c8aad.camel@cybertec.at> (raw)
In-Reply-To: <18173-c971c32eb961e810@postgresql.org>
References: <18173-c971c32eb961e810@postgresql.org>
On Mon, 2023-10-30 at 13:24 +0000, PG Bug reporting form wrote:
> PostgreSQL version: 16.0
>
> postgres=# CREATE TABLE test_v(id int,name varchar(30));
> CREATE TABLE
> postgres=# insert into test_v values(9,'abc'),(9,'def'),(9,'gh'),
> (9,'gh');
> INSERT 0 4
> postgres=# explain (costs off) select distinct
> (id,name,'D3Q84xpymM',123,'123') from test_v;
> QUERY PLAN
> -------------------------------------------------------------
> Unique
> -> Sort
> Sort Key: (ROW(id, name, 'D3Q84xpymM', 123, '123'))
> -> Seq Scan on test_v
> (4 rows)
>
> postgres=# select distinct (id,name,'D3Q84xpymM',123,'123') from test_v;
> ERROR: could not identify a comparison function for type unknown
This is not a bug. You probably want to remove the parentheses.
Yours,
Laurenz Albe
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To: pgsql-bugs@postgresql.org
Cc: laurenz.albe@cybertec.at, 409800246@qq.com, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18173: ERROR: could not identify a comparison function for type unknown
In-Reply-To: <52e52bddd9d5396ca07f103f799518f82e2c8aad.camel@cybertec.at>
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