Riak's design explicitly falls into the AP corner of the widely cited CAP Theorem. This means that it gives up consistency. The scenario that you are asking about involves consistency in a deep way, and so is tricky to do with Riak.
Your life will be much easier if you visit http://blog.nahurst.com/visual-guide-to-nosql-systems and pick a system that supports consistency from the get go for the part of your work that requires those semantics. On Thu, Apr 21, 2011 at 11:47 AM, Jeffrey Kesselman <jef...@gmail.com> wrote: > Hi Guys, > > I've been studying Riak and am considering a major technology base > shift in a project I've been working on for more then a decade (the > Project Darkstar/RedDwarf game server.) As may coming to this from a > strict RDBMS background I am sure, I am trying to wrap my head around > vector clocks. > > I read the "Why vector clocks are reasy" blog and think i follow that. > My question is this: what if I have multiple data changes to multipel > data structures that all have to remain in sync (be atomic)? Which > data strictures are involved in any one change is not predictable. I > can allow for eventual resolution of that consistent state, and even > change from one consistent state to another, but the state must always > be consistant. This is easy to do in a traitional transaction btu im > having trouble with the VC equivalent. > > As a gedanken experiment picture two players trying to buy a limited > commodity of which there is only 1 available. In both cases they are > attempting to decrement their money, remove the object from the store > inventory, and add it to their own inventory. Only one can succeed as > these 3 actions must be atomic. It is okay for both to initially > think they succeeded as long as next time we go to look at these > states they resolve themselves. (Assume a resolution mechanism, for > argument we can say earliest timestamp wins.) > > This needs to be a general solution, knowledge of what the data > structures are or do *cannot* be part of the solution. This means > that the item cant itself have an "owner" field which is part of the > disambiguating logic. Disambiguating all structures (the 2 player > inventories, the store inventory and the two players money values) > must be done without any semantic knowledge of what the data is for. > > Is this possible? Can someone lay out the solution based on the > simpel case above? > > Thanks > > JK > > > Note that I need a general solutioso any > > -- > It's always darkest just before you are eaten by a grue. > > _______________________________________________ > riak-users mailing list > riak-users@lists.basho.com > http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com > _______________________________________________ riak-users mailing list riak-users@lists.basho.com http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
