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recent bookmarks from jmThe trouble with timestamps2013-10-14T09:45:54+00:00
http://aphyr.com/posts/299-the-trouble-with-timestamps
jmTimestamps, 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 riakhttps://pinboard.in/https://pinboard.in/u:jm/b:dcc3c0071909/Riak, CAP, and eventual consistency2013-04-20T22:03:34+00:00
https://gist.github.com/macintux/5418295
jmAs Brewer's CAP theorem established, distributed systems have to make hard choices. Network partition is inevitable. Hardware failure is inevitable. When a partition occurs, a well-behaved system must choose its behavior from a spectrum of options ranging from "stop accepting any writes until the outage is resolved" (thus maintaining absolute consistency) to "allow any writes and worry about consistency later" (to maximize availability). Riak leans toward the availability end of the spectrum, but allows the operator and even the developer to tune read and write requests to better meet the business needs for any given set of data.]]>riak cap eventual-consistency distcomp distributed-systems partition last-write-wins voldemort allow_multhttps://pinboard.in/https://pinboard.in/u:jm/b:1bded8180d0b/