Open Stack

On 13/06/2012, at 3:31 AM, Jay Pipes wrote:

> This isn't necessarily true. Nova's compute layer goes through a number of steps to ensure a semi-transactional nature to certain operations like resizing. Certain times a query needs to indicate that it intends to make a reservation of resources (see quota/reservation system now .. this is the SELECT FOR UPDATE paradigm) and other times, the query doesn't care about such things. In the latter case, there aren't expectations that the list returned is 100% accurate according to the state of the database at a particular timestamp of when the transaction occurred. In this case, filters and optimistic pagination works perfectly fine, IMHO.

That might work, but we need to be crystal-clear about the semantics of what we're giving back; having it understood between OpenStack projects isn't good enough. 

I.e., we're not building the APIs just for Horizon; they're for lots of folks, and subtle semantics -- even when well-documented, much less when they're not -- are often misunderstood.

Cheers,

--
Mark Nottingham   http://www.mnot.net/