jm + aphyr + distributed   2

The trouble with timestamps
Timestamps, as implemented in Riak, Cassandra, et al, are fundamentally unsafe ordering constructs. In order to guarantee consistency you, the user, must ensure locally monotonic and, to some extent, globally monotonic clocks. This is a hard problem, and NTP does not solve it for you. When wall clocks are not properly coupled to the operations in the system, causal constraints can be violated. To ensure safety properties hold all the time, rather than probabilistically, you need logical clocks.
clocks  time  distributed  databases  distcomp  ntp  via:fanf  aphyr  vector-clocks  last-write-wins  lww  cassandra  riak 
october 2013 by jm
Call me maybe: Carly Rae Jepsen and the perils of network partitions
Kyle "aphyr" Kingsbury expands on his slides demonstrating the real-world failure scenarios that arise during some kinds of partitions (specifically, the TCP-hang, no clear routing failure, network partition scenario). Great set of blog posts clarifying CAP
distributed  network  databases  cap  nosql  redis  mongodb  postgresql  riak  crdt  aphyr 
may 2013 by jm

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