"rkusenet" <rkusenet_at_yahoo.com> wrote in message
news:3l4k0cF107mn3U1_at_individual.net...
>> So creating an index on a foreign key should not be automatic.
>
> While I agree with you, I would add that for code lookups like Title (Mr,
> Mrs, Ms)
> I would rather go with a check constraint than a FKY. Anything with a low
> cardinality
> and known static values should be handled in a check constraint. At least
> I
> would.
>
The fact is that almost all modeling tools will show a foreign key
relationship to the lookup table as part of 3rd normal form. When the DDL is
generated by the tool, it will generate indexes for these relationships
automatically (incorrectly IMO). The result is poor performance on inserts
of the dependent table.
The result is that many schemas have way too many indexes that will never be
used, and of course invariably there are at least a few indexes missing.
Received on Sun Jul 31 2005 - 13:45:17 CDT
