Re: Foreign keys

On Fri, Aug 27, 2004 at 09:31:51AM +0100, Steve Tucknott wrote:
> PostGreSql 7.4.3
>
> Am I right in assuming that a foreign key on a table does not explicity
> create an index on that column on the foreign table? I can see via the
> \d on the table that the foreign key exists, but accessing the table on
> that column seems to use a sequential scan.

Adding the foreign key won't add the index itself, but I believe that
foreign keys can only be declared on columns declared unique.
Since declaring columns unique implicitly creates an index on them, if
you can legally declare the foreign key then "\d" should show that
the foreign key's index already exists.

It sounds like sequential scan is being used for a completely
unrelated reason.

- Jeremy