Hi hackers,
can this be made a TODO?
Thanks
--
Markus Bertheau <[EMAIL PROTECTED]>
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Markus Bertheau wrote:
Hi,
PostgreSQL doesn't allow the creation of a foreign key to a combination
of fields that has got no dedicated unique key but is unique nonetheless
because a subset of the combination of fields has a unique constraint.
[snip example]
Is this on purpose? I think the foreign key should be allowed. Creating
an extra unique key only has a negative impact on performance, right?
As you say, the uniqueness is guaranteed so there's no good reason why
it couldn't be made to work. It's probably more of an implementation
issue. Unique constraints are implemented with an index, so I'm guessing
the FK code assumes there is an index there to check against.
--
Richard Huxton
Archonet Ltd
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