Think hard before locking a table while a user is dawdling over his reservation.
The feature you are dealing with is database "isolation level<http://en.wikipedia.org/wiki/Isolation_%28database_systems%29>" and is the subject that fills volumes of database theory. From what you describe I think you want the "repeatable read" level. I do not know enough about GAE to tell you which levels it supports. -- Joe B. On Thursday, November 29, 2012 2:18:47 AM UTC-8, José Manuel López Muñoz wrote: > > I'm making a room reservation system in Web2Py over Google App Engine. > When a user is booking a Room the system must be sure that this room is > really available and no one else have reserved it just a moment before. To > be sure I make a query to see if the room is available, then I make the > reservation. The problem is how can I do this transaction in a kind of > "Mutual exclusion" to be sure that this room is really for this user? > > Thank you!! :) > --
