Subject Foreign Key index optional?
Author Ray Drew
There was some discussion last year on the use of foreign keys referencing
small control tables and the fact that the foreign key's mandatory index
would slow things down. I think it was mentioned that the foreign key's
index would be made optional. Are foreign keys' indexes optional now?


Ray Drew

> At 02:54 AM 17-06-01 +0200, Helen Borrie wrote:
> Indexes on small ("control") tables won't slow anything down, since
the tables are usually pretty static anyway and you are not going to
be performing huge bulk inserts or deletes to them. Some would say
that it's not worth indexing them but you are using IBO, which makes
good use of indexes.
> Making foreign keys on other tables that reference these small
tables will DEFINITELY slow things down - IB will form long duplicate
chains in the index tree of the mandatory index and wreck
performance. Instead, make composite indexes on such columns,
combining the lookup column + the primary key.

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