On Sat, May 17, 2008 at 2:25 PM, Julien Cornuwel <batosai at batosai.net> wrote: > I've been reading DB4O's whitepaper (mentionned in Toad's post) and I'm > wondering if I could use it for the WoT plugin. I could get rid of Derby > and it would make the deployment simpler if db4o is shipped with freenet. > > Query possibilities are sufficient to my needs but I've got a few problems : > > > With a RDBM, I can simply do the calculation of scores in the database > (with a trigger and stored procedures). > With db4o, persistence would be easier but I worry about memory > consumption if I have to load every identities in memory each time a > trust value is updated. An identity is about 200-250B. You see the > problem if we have 1.000.000 identites !
I know perst, and I think db4o works similar. When you load persistent objects, the engine takes care what objects fit in the memory cache. So you can hold millions of objects but not all of them are always in memory. This can lead to longer access times in reality. > > The other problem is how to store the trust values. With derby, I simply > have 2 tables, one with identites, the other with the trust values and > ids if the truster and the trustee. How can I do that with an OO > database ? The only idea I have is : > Create a class Trust containing reference to the trusted identity and > trust value, and store a list of Trust objects in every identites. I > can't figure how bad it would be for the memory consumption. > In perst I use different storages. Each one can have a different cache size. This way I can spread the load. But it is also possible to hold all objects in one storage. > > Do you think it is feasible and worth the work ? > > > _______________________________________________ > Devl mailing list > Devl at freenetproject.org > http://emu.freenetproject.org/cgi-bin/mailman/listinfo/devl > -- __________________________________________________ GnuPG key: (0x48DBFA8A) Keyserver: pgpkeys.pca.dfn.de Fingerprint: 477D F057 1BD4 1AE7 8A54 8679 6690 E2EC 48DB FA8A __________________________________________________
