Yes there is only one instance of the object in BigTable. If a request calls put() on an object what happens is:
1) the object is created/updated in the Datastore 2) all the index tables are updated. 3) the put() returns After the put call you know that a query for the object in the same request handler will be retrieved correctly. If another request handler does a query for the same kind it depends when the query is executed in relation to the put() call. before 1) you get the old version and the old index table between 1 and 2) you get the new version and the old index table (update), or not found (create) after 2) you get the new version and the new index table But if these requests come from a single user that does not do simultanious requests this index-situation does not apply 2009/1/1 bowman.jos...@gmail.com <bowman.jos...@gmail.com>: > > Trying to track down a very inconsistent issue with gaeutilities > session. I don't know enough about the backend to make some guesses, > so am asking. > > When I enter an entity into BigTable, is that the only instance that > exists and all front ends that users hit will read that same entity, > or is there some sort of data duplication/caching that could mean that > the entity is not available to an instance that the user is hitting? > > Session works by sending a cookie with a session token, and then that > token is stored in the datastore. Every request the cookie is compared > against the datastore to determine if the user is logged in. There is > some memcache usage, but if the data is not found in memcache, the > datastore is checked. > > I believe I've seen the same issue with a couple other processes I > have in place for oauth/open id logins, where I've gotten strange > random results of data not being found, but it's too inconsistent to > track down. > > I can bang on the gaeutilities session without any problems. I in fact > set up some javascript request buttons on the session demo to try and > break it, haven't been able to replace the problem there. > > The application where I do see the problem is a django 1.0 > application, using appengine patch. Not sure why or how that would > matter but there you go. > > I'm going to write some test scripts against that site to see if I can > get any luck duplicating the issue in a reliable sense in the next few > days. > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to google-appengine@googlegroups.com To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~----------~----~----~----~------~----~------~--~---
