> >...indexing a varchar (300) field. It's too big to index -
> > no problem. Write a 'before insert' trigger [that checks for

duplicates]

> >
> >...except that it won't work like an index because it can't see
> >uncommitted values... If I could dirty-read this wouldn't be a
> >problem. If dirty reading is 'always bad' then how come indexes
> >can do it?!?!? grin
>
> Because it's the Mommy, that's why.
>
> Seriously, the right answer is to allow longer index keys. And we
> will. We would have done it sooner, but some curmudgeon insisted
> that there be no significant ODS changes in Firebird 1 and 1.5, and
> changing the way indexes work is really an ODS change. The reason
> for the rule is that we were learning the code, in many cases learning
> about open source, and trying to establish a solid base on which
> to build future versions. If we went off in a bad direction and
> really screwed something up, users could go back to an earlier
> version very simply if it had a common ODS. We've crossed that
> boundary. We have two reasonably stable releases and it's time to
> fix some of the really aggravating problems - especially index key
> size.

Add expression indices then :-)

You can SUBSTRING an index value - just like in MySQL.

With regards,

Martijn Tonies
Database Workbench - developer tool for InterBase, Firebird, MySQL & MS SQL
Server.
Upscene Productions
http://www.upscene.com