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From Antony Blakey <>
Subject Re: couchdb transactions changes
Date Tue, 10 Feb 2009 00:29:18 GMT

On 10/02/2009, at 10:30 AM, Paul Davis wrote:

>> Compaction and revision stemming (which is required to avoid  
>> unbounded
>> growth) make intermediate states inconsistent because they can  
>> delete either
>> the data of a document rev or the document rev itself. In the face of
>> compaction, it's possible for consistency to only be achieved when  
>> the
>> replication reaches the same MVCC commit point that the compaction  
>> was
>> operating against. Revision stemming has a similar effect, although  
>> it has
>> the further issue of being automatic i.e. not scheduled.
>> That's ignoring replication failure, either temporary or permanent,  
>> which
>> further complicates the picture. Given that intermediate states are  
>> not
>> necessarily consistent, anything that leaves you in an intermediate  
>> state
>> without a way forward, repudiates the guarantee of Eventual  
>> Consistency.
> I'm pretty sure the rest of this is wrong though.

I mean no offense, but I'm looking for something more than 'pretty  
sure'. I'm trying to work through these issues so that I understand  
the formal model and design intention completely and properly.

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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