On Tue, Apr 11, 2006 at 05:01:17PM -0400, Tom Lane wrote: > David Fetter <[EMAIL PROTECTED]> writes: > > On Tue, Apr 11, 2006 at 04:35:05PM -0400, Tom Lane wrote: > >> More realistically, though, the theoretical point that you can do > >> arbitrary calculations by turning loops into recursive SQL > >> functions is mostly just theoretical, and the reason is that you > >> won't be able to loop very many times before running out of stack > >> space. (On my machine it looks like you can recurse a trivial > >> SQL function only about 600 times before hitting the default > >> stack limit.) If you have an exploit that involves moderate > >> amounts of calculation within the server --- say, brute force > >> password cracking --- the availability of a PL will render that > >> exploit actually practical, whereas with only SQL functions to > >> work with it won't be. > > > The function I sent memoizes to a table, which avoids the stack > > space problem you mentioned. > > In general that's not possible, and even for the specific case, it > still looks to me like fib(n) will use O(n) recursion levels if the > table is initially empty.
I don't get your not getting this 'cause you're a very smart guy. Are you under the impression that an attacker will stop because he has to try a few times? Cheers, D -- David Fetter <[EMAIL PROTECTED]> http://fetter.org/ phone: +1 415 235 3778 AIM: dfetter666 Skype: davidfetter Remember to vote! ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org
