[Zope] Large ZODB vs SQL + cataloging issues

[Felix Ulrich-Oltean]

Hi

I am looking to build a system to hold 100s of sites, each of which
holds several catalogues (as in on-line shopping, not ZCatalogs).  How
large can ZODB realistically go?  At which point would it make more
sense to hold data in a n RDBMS and use sql from Zope instead?

Also, a related note is:  If I have 100 online shops running from my
Zope isntance, and one if them is a thousand times bigger than the
others, how will the ZCataloging and general traffic on the big site
affect the others?

I'd like to just use the ZODB, but I have to convince some people that
it will perform.  Any case studies, tests, benchmarks, articles, etc
would be very useful.

TIA,

Felix.