Tom Insam

Links on distributed databases and replication

Reading a RWW article on non-relational databases, I came across the term 'Eventual Consistency' which is something I've seen a couple of times recently. I immediately and loudly demanded that mattb tell me what it meant. He proceeded to dump waaay too much reading material on me almost instantly, which tells me that I'm onto something. I hereby relay the following, so that I don't lose the links:

  • Eventually Consistent - Revisited by Werner Vogels (Amazon CTO). A nice overview of what the term means, including a list of things that you take for granted and aren't guaranteed, things you don't take for granted and aren't guaranteed, and things that it never occurred to you to doubt, that aren't guaranteed. For instance...

  • ..suppose you wanted to sync with a database traveling in a different relativistic frame? Well, ok, maybe slightly less serious than that, but things can still disagree on what the time is. Time, Clocks and the Ordering of Events in a Distributed System.

  • Amazon S3 Availability Event: July 20, 2008 - Amazon S3 fell over a few months ago. I remember this because all my twitter icons went away. Anyway, this is why. Interesting in the context of the other two.