Originally posted by: DrPizza
I'm not sure, but I believe that a forum this size is handled by multiple servers. Maybe the servers are out of sync? i.e. the time on one differs by a little bit from the time on the other?
My guess is either a clock out of sync, or cached values for the post ID field. I don't know if they're using SQL Server or Oracle, and I don't know how SQL Server handles autonumber fields on DBs that are spread across multiple servers, but on Oracle it'll cache a certain number of values (I believe 20) by default. So if you hit one server you'll get 1, 2, 3, on the second server you'll get 21, 22, 23, etc. getting multiple numbers at one time has a performance benefit, but then of course you can't rely on the IDs being in chronological order. That's the sort of thing that someone could have changed to fix a performance issue without considering the full impact of the change.