Subject Re: [firebird-support] Possible solution to low selectivity index and Foreing keys trouble?
Author Arno Brinkman

> >Why dont just allow to select the index to be used by a RI constraint?
> >I dont know FB internals, so i ask developers if that is possible, and
> >be a temporary solution for that trouble.
> I know a bit about FB internals, and I assure you, at the moment a foreign
> key index is treated differently - especially in idx.cpp - from a normal
> index. Making the change you suggest would require changing the way
> key constraints are enforced. Not a bad thing, but not a simple thing

Because Firebird is developed/maintained with the idea to be as much
self-tuning as possible. I think a index should always be created, but
currently there are performance problems (many duplicates) due the way the
indexes are designed internally in the system. Also the optimizer doesn't do
his job good enough sometimes. The slow index stuff on duplicates will be
fixed in the Firebird 2.0 release, so that's already good start and i'm sure
the optimizer will follow.
All IMO of course :)

Arno Brinkman

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