Absolute consistency

Les Mikesell lesmikesell at gmail.com
Wed Jan 11 12:56:08 EST 2012


On Wed, Jan 11, 2012 at 10:39 AM, Ian Plosker <ian at basho.com> wrote:
> Les,
>
> In Riak, there is no single primary copy considered the canonical version.
> For each key, there will be N (3 by default) partitions responsible for
> storing the associated value. In effect, there are N primaries for any key.
> This is how Riak makes its availability guarantees, as well as why "absolute
> consistency" is difficult.

But who makes the decision that a partition needs to migrate and where
a key is at any time during that migration?  That isn't independently
decided by each node, is it?  And if you have an authority for that,
why can't a client ask that authority to control ordering of
operations for certain things where the client is willing to trade the
time it might take for atomicity.



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