4 ms·
Is eventually known consistency even possible if at any point while the notification of consistency is being transferred to you, the system can enter a non/even
by eis 15y ago
Is eventually known consistency even possible if at any point while the notification of consistency is being transferred to you, the system can enter a non/eventual-consistent state again?
- cperciva 15y agoBy "eventually known consistency" I don't mean "at some point I will know that the system is consistent"; rather, I mean "at some point I will know that the system is consistent with respect to operation X" (or alternatively "... with respect to all operations performed before time T").
- nknight 15y agoThere's actually two distinct things you might want to know: 1) The current state of the system. 2) Whether the current state of the system is equal to or later than one reflecting your change. #1 is technically unknowable without a locking mechanism, but #2 is theoretically possible. Assuming reliable time synchronization, your worst-case scenario would be a timestamp on every record, and checking the timestamp on each node (you can do this with Cassandra, for example).