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From Antony Blakey <>
Subject Re: Trouble with replication
Date Fri, 30 Jan 2009 05:23:16 GMT

On 30/01/2009, at 9:49 AM, Chris Anderson wrote:

> What's happening in this scenario is that B is not getting any revs
> from A. Replication is one-way. I think if you always trigger
> replication both ways, then your nodes will be consistent (assuming
> they accept the same set of updates as valid).

If you have > 2 nodes then that is no longer true. Consider three  
nodes A, B and C where

A: has a validation function F
B: a document that is invalid under F

Replicating B -> C, A -> C is different than A -> C, B -> C, and there  
is no global steady state that can be reached.

Without these non-functional additions, A, B, C will tend to a global  
steady state assuming full replication coverage, regardless of  
ordering. At least that's what I assume from the wiki statement about  
the determinism of conflict resolution. Have I made the wrong  
assumption about that?

Antony Blakey
CTO, Linkuistics Pty Ltd
Ph: 0438 840 787

The intuitive mind is a sacred gift and the rational mind is a  
faithful servant. We have created a society that honours the servant  
and has forgotten the gift.
   -- Albert Einstein

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