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From Antony Blakey <>
Subject Re: couchdb transactions changes
Date Mon, 09 Feb 2009 00:14:29 GMT

On 09/02/2009, at 1:08 AM, Damien Katz wrote:

> Nope, each individual read operation gets a snapshot of the  
> database. When you are replicating, there is one read operation for  
> every document that must be sent. Each read request gives you a new  
> MVCC database.

This prompts the question - why not?

It seems to me that the consistency characteristics of replication  
could be improved if a) MVCC boundaries were created by update  
operations and b) a given replication was bounded by the latest MVCC  
state available when the replication was started i.e. replication  
cannot race with updates. I presume replication cannot use a single  
MVCC state because it needs to see revisions? If revisions are visible  
within a state, then my question would be why replication doesn't use  
a single MVCC state.

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

Borrow money from pessimists - they don't expect it back.
   -- Steven Wright

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