isolation level

[Guest_imported]

hi!

i wrote a little application, that involves a number of clients
and a database-server. the clients query the database, get some
result, then disconnect from the database, do some computation,
then re-connect to the database and write back their results.

my quetsion is: what kind of isolatoin level should i use
(uncommited read, commited read, repeatable read, serializable)?
is there any "thumb-rule" of when to use which isolation level?
what special precautions do i have to take using uncommited read
(for better performance) or repeatable read???

you would help me alot.

thanks in advance,
michael