So if we hold WS(C) until we receive commit messages for WS(A) and WS(B), will that meetAnd that is IMHO not synchronous. C does not have to wait for A and B toLets say we have systems A, B and C. Each one has some changes and sends a writeset to the group communication system (GSC). The total order dictates WS(A), WS(B), and WS(C) and the writes sets are recieved in that order at each system. Now C gets WS(A) no conflict, gets WS(B) no conflict, and receives WS(C). Now C can commit WS(C) even before the commit messages C(A) or C(B), because there is no conflict.
finish the same tasks. If now at this very moment two new transactions
query system A and system C (assuming A has not yet committed WS(C)
while C has), they will get different data back (thanks to non-blocking
reads). I think this is pretty asynchronous.
your synchronous expectations, or do all the systems need to commit the WS in the same order
and at the same exact time.
It doesn't lead to inconsistencies, because the transaction on A cannot do something that is in conflict with the changes made by WS(C), since it's WS(A)2 will come back after WS(C) arrived at A and thus WS(C) arriving at A will cause WS(A)2 to rollback (WS used synonymous to Xact in this context).
Right
No, however I guess I need to adjust my slides to include your definition of synchronousHope this doesn't add too much confusion :-)
replication. ;-)
Darren
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