Buenas notches (that's not my language! hahaha) > Oh yes, I didn't think about the lake. And the late-sync protocol does > not specifies to be water-resistent :). You've got the reason. Maybe it's > better to make the unplugged server to rollback, and the cluster to > bufferize logs from entire transaction for its future recovery. > Another thing about it I was thinking today is to ensure agreement of > buffer, that is, to replicate the buffer log for all servers in late > sinchronization. That's because of to prevent another fault to damage the > global consistence. What do you think? > > [Peter]Well we'll need somesort of a global log anyway. Not only for these > un- and redo stuff but also for replication (see next email). > > Yes, of course. I think *global logs* must be another starred point to be submitted to our analysis (wow, how many things!!!) > > By the way, in general manner do you agree with late synchronization? > > [Peter]I would agree under the following conditions (feel free to > disagree): > > 1.) RDD table can always be late synct (since they are only management > tables and 90% of queries against these tables are selects) > > Yes, I agree fully. Late sync must be applied in some situations to help, and not to degrade. 2.) There is an upper bound for late sync. This means that there is a some > time (e.g. 10sec.) where the sync commands can be delayed. but after this > time the sync mußt be done > > I can't understand it clearly. 3.) LDD tables are only partialy late synct. The only syncing to do is the > GI update right? > > I think so. > So a late sync could only be done if there was an agreement on the u/f/p > keys. > > I agree. Maybe we will need to have means to ensure agreement within dynamic operations. Maybe a flag per table, with a agreement protocol, I don't know yet. But it must be a trusted mean to ensure a safe late sync. AND Inserts and updates are imidiatly synct and delets are late synct. > > In true, I think late sync for I/U/D might be allowed *only *if the faultous server and the targeted server are different. That's important to avoid to prohibit full access to the island-server, during a network fail, for example, and at the same time, to ensure consistence. This is because if there was a deletion the remote server would still > query the server but the server would only return an empty set. Inserts mußt > be synct in time because there is a kind of filter that the GI can set to > optimize the number of remote server queried. Same applies for updates. > > > This I also did not understand clearly. -- Sem mais, Fabricio Mota Oda Mae Brown - Aprecie sem moderação. http://www.odamaebrown.com.br