From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alex Zeng <Alex.Zeng@datam.co.nz>
Cc: pgsql-bugs@lists.postgresql.org <pgsql-bugs@lists.postgresql.org>
Subject: Re: information_schema.constraint_column_usage shows wrong table name
Date: Tue, 10 Aug 2021 11:51:23 -0400
Message-ID: <3788089.1628610683@sss.pgh.pa.us> (raw)
In-Reply-To: <SY4PR01MB7201EE307A0E5F28C4BF26B8B7F79@SY4PR01MB7201.ausprd01.prod.outlook.com>
References: <SY4PR01MB7201EE307A0E5F28C4BF26B8B7F79@SY4PR01MB7201.ausprd01.prod.outlook.com>
Alex Zeng <Alex.Zeng@datam.co.nz> writes:
> When creating a constraint from table A to table B, the table name and column name in information_schema.constraint_column_usage shows table B. That makes impossible to check whether a constraint exists as we can have a constraint from table C to B and they will have same value in information_schema.constraint_column_usage.
The SQL standard says the purpose of this view is to
Identify the columns used by referential constraints, unique
constraints, check constraints, and assertions defined in this catalog
and owned by a given user or role.
so I think the view is showing the column name it is supposed to,
ie the referenced column name not the referencing column name.
The key_column_usage view might help you with the other thing.
regards, tom lane
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To: pgsql-bugs@postgresql.org
Cc: tgl@sss.pgh.pa.us, Alex.Zeng@datam.co.nz, pgsql-bugs@lists.postgresql.org
Subject: Re: information_schema.constraint_column_usage shows wrong table name
In-Reply-To: <3788089.1628610683@sss.pgh.pa.us>
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