You know.. How fast is LDAP compared to using SQL? For one thing, LDAP is optimised for reads rather than writes.
I would believe that LDAP is more suitable in this case.
Writes are only needed when adding users and that doesn't happen as often as reads.
You are completely right. However, this was long time ago. As I said, today we'd go with LDAP, no questions asked. Back then, the dicision which way to go wasn't that clear. We tested both SQL and (what was available of) LDAP servers, and Oracle was better fit. So it wasn't like "SQL sounds cool", it was "built the test server, place it under load our production servers would generate, optimize it, see what we get out of it". LDAP servers that were available back then simply didn't deliver numbers we needed. Oracle database did.
Also, have in mind that ISP will want to keep logs in a format that is easy to get various statistics out of it. SQL database is perfect for something like that (so basically, the system wasn't used only by mail server, it was also used to authenticate dial-up users, and keep track of usage logs -- not really your classic 90% read environment, there were lots of writes too). Oracle delivered both read and write performance, so why complicate things by keeping data in two places.
-- Aleksandar Milivojevic <amilivojevic@xxxxxx> Pollard Banknote Limited Systems Administrator 1499 Buffalo Place Tel: (204) 474-2323 ext 276 Winnipeg, MB R3T 1L7
