Ruby on Rails

There's some really interesting approaches in all of these emails.

I like this one the best. I haven't learned how to setup 2 databases
in rails... but is this complicated to do? I guess I could make a
database just like this person is doing, put all the thesaurus lookups
in it, and then keep it running just like any other database.

I want to avoid doing a ruby<->java bridge if I can. The last thing I
want is some bloated java process needing 512 megabytes of ram just to
do its think without throwing some kind of out of permgem space or out
of memory errors :/ At least if it's all in rails, I can just dedicate
all of extra ram to rails and my database.

Are the in-memory databases fairly quickly, such as sqlite? I've not
used it mysql. If it can take do at least 1000 individual select
statements very quickly (like less than a second), then that could
work.