> I have a couple of databases with 20 million + rows in 2 or 3 tables linked
> by indexed double precision fields. I have not needed to link them with a
> foreign key constraint. I have PK's on double precision fields in each of
> the tables. As far as speed goes, lookups on 2 joined tables takes about
> 0.062 seconds. Fetching 10K-100K records at a time takes me about 8-30
> seconds.

Thanks for all the great replies. They will surely help in deciding on
the best solution for the project.