Limiting database size ...

Hi!

I'm working on an ISP, and we're testing Postgres to offer Database
Services to our clients.

We like to limit the maximum database size for each client (1 database
for client), but as far as I know postgres hasn't this functionality.

I've also tried to limit this size using system quotas but it doesn't
work because to control this space I need that the files of the database
(those under the data/base/xxx) owns to the user ant then postgres
doesn't recognise them (I'm also afraid because i don't know what could
happen to the database consistence if the operating system doesn't
permit to complete an operation in course).

Someone has the same problem?
How can I make that?
What would happen to the consistence if the quota is full while postgres
is writing?

Thank you, and sorry for my english :(
--
********************************************************
Daniel Rubio Rodríguez
OASI (Organisme Autònom Per la Societat de la Informació)
c/ Assalt, 12
43003 - Tarragona
Tef.: 977.244.007 - Fax: 977.224.517
e-mail: drubio@oasi.org
********************************************************