4 ms·

I'm saying read replicas are not instantly in sync with their masters. Updates are asynchronously copied to the replica.

• peterwwillis 9y ago
  Or, you know, use synchronous replication, or semi-synchronous, or a different asynchronous model that isn't weakly consistent such as distributed transaction logs, write-read consensus, complicated locking mechanisms, etc
  • saryant 9y ago
    All of these solutions are still battling the fact that distributed systems are hard and there's a tradeoff to every decision. If you use synchronous replication, you now require at least two systems to commit a write, so you've increased the chance that your commit will fail. Maybe that's the right choice—but it's a tradeoff and the decision ultimately rests in your business requirements. My point is simply that there is no magic bullet in ensuring that all relevant systems have the same answer to the same question at the same time.
    • deleted 9y ago
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