Databases: Which one's right for me?

[Aaron Watters]

re: jeremy's reply...

I find the Gray and Reuter definition confusing.  To my mind isolation means
serializability and if you don't have serializability (at least as an 
option)
you don't have isolation.  Transactions don't have to be complex to 
cause serious
problems in read-committed mode:  the classic example is a debit of 
$1000 for
checking account 123 running at the same time as a credit for $4000 for 
checking
account 123.  If both transactions run at the same time and read the 
same previous
(committed) balance and they both complete but the first one completes last
then the customer is screwed to the tune of $4000.  This is only the 
simplist
problem -- for transactions involving complex data structures the 
problems can
be much more subtle than that (and more difficult to correct).

   -- Aaron Watters
===
in theory, theory is the same as practice.
in practice, it's more complicated than that.