Re: Why does Postgres allow duplicate (FK) constraints

Thomas Kellerer <spam_eater@gmx.net> wrote:
> Alban Hertroys, 26.03.2013 17:17:
>> It can make sense during a maintenance window, if you create a new
>> (redundant) FK constraint concurrently to replace the existing one.
>> If you'd first remove the existing constraint, you're allowing FK
>> violations until the new constraint has finished creating its index.
>>
>> This happens for example if you want to use a different index
>> algorithm, say a gist index instead of a btree index, or if the
>> initial index has gotten corrupt somehow and it needs reindexing.
>
> I can understand this for indexes, but a foreign key constraint does not create
> one.

I once saw a case where this needed to be done because the
dependency information somehow became inconsistent.

--
Kevin Grittner
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