database types

[David Wright]

Henrique, who maintains the Debian cyrus-imap packages (and does a very 
good job of it) just changed the MBOX and SEEN databases to use skiplist 
(from db3 and flat). I had never thought about this issue before.

Can someone explain what advantages and disadvantages one has from the 
different database types? And what is a skiplist anyway? I'm familiar 
with flat files and the sleepycat databases, but I've never heard of a 
skiplist.