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From Antony Blakey <>
Subject Re: Proposal: Extending immutability
Date Mon, 12 Jan 2009 12:34:20 GMT

On 12/01/2009, at 10:26 PM, Noah Slater wrote:

> On Mon, Jan 12, 2009 at 05:15:39PM +1030, Antony Blakey wrote:
>> --- Revised Proposal ---------
>> Each document, whether canonical or derived, has a globally unique
>> identity consisting of a UUID and the document ID.
>> In the case of a canonical document, the UUID is the UUID of the
>> database (or cluster), which is assigned when a database is created.
>> In the case of a (derived) view map result, it is the UUID of the map
>> function (not the design doc), which is assigned to each map function
>> (i.e. view) in a design doc when the design doc is created or  
>> updated.
>> Furthermore, there is a triple {UUID, document id, document rev} that
>> globally identifies a document at a given point in time. The key
>> characteristic being that a {UUID, id, rev} identifies an immutable
>> value.

For views it is slightly more complex. At a first blush you need to  
include the key because a given map function can emit multiple view  
rows per document. But from a theoretical standpoint it's worse than  
that, because the map function can emit multiple view rows with  
identical keys but different values. This is a pathological scenario  
however, and IMO a generic middleware that doesn't deal with that  
situation is still extraordinarily useful.

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

A reasonable man adapts himself to suit his environment. An  
unreasonable man persists in attempting to adapt his environment to  
suit himself. Therefore, all progress depends on the unreasonable man.
   -- George Bernard Shaw

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