MongoDB Is Still Broken by Design 5-0
My score after the first period was 4-1. But Emin Gün Sirer contested the 1 in the follow up post to 10gen’s reply:
Until recently, MongoDB did not talk about requestStart() and requestDone() in any context except when talking about how to ensure a very weak consistency requirement. Namely, if you don’t use this pair of operations, then a write to the database followed by a read from the database, by the same client, can return old values. So, I write 42 for key k with a WriteConcern.SAFE, read key k, and get some other number, because the Mongo driver can, by default, very well send the first request to one node over one connection, and the second one to another, over another connection. So requestStart() and requestDone() were billed as a mechanism to avoid that scenario; I saw no mention that they were required for correctness in multithreaded settings. I bet there is plenty of multithreaded code that does not follow that pattern. Such code is broken; if you’re a Mongo user, it’d be a good idea to check if you ever use getLastError without a bracketing requestStart() and Done().
5-0.
Original title and link: MongoDB Is Still Broken by Design 5-0 (©myNoSQL)
via: http://hackingdistributed.com/2013/02/07/10gen-response/#id2
