I am mainly using it the context of initially populating a database. So there isn't any danger of a race because there is only one user.
On Nov 5, 2012, at 12:47 PM, Jens Alfke <[email protected]> wrote: > > On Nov 5, 2012, at 10:22 AM, Kevin Burton <[email protected]> wrote: > >> I am calling CreateDocument<Document>() but I suspect that testing if the >> document exists first may perform better in the long run. I am using >> DreamSeat for my driver but I suspect other drivers have a similar "test". >> My problem is that I don't know what to test for and I am unfamiliar with >> the available methods. Any one successfully use such a pattern (preferably >> with DreamSeat) that tests for existence then creates if the document >> doesn't exist? Keep in mind I don't initially have an id. Thank you. > > I don’t know anything about that particular API, but in general, > check-then-create doesn’t work well in a concurrent environment. It’s prone > to race conditions where something else creates the resource in between your > check call and your create call. (The canonical example is checking whether a > file exists, then creating the file, which is a classic old security hole in > privileged Unix tools.) > > —Jens
