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From J Chris Anderson <jch...@gmail.com>
Subject Re: Newbie: Locality of Reference in Couch
Date Wed, 26 May 2010 22:39:57 GMT

On May 26, 2010, at 1:53 PM, Robert Buck wrote:

> Hi Folks,
> 
> Thank you for kindly answering my last round of questions. Here is
> another question related to Couch:
> 
> What sort of locality of reference exists in Couch with respect to
> retrieval of state ? Is locality of reference solely at the document
> level, or is locality of reference also exhibited elsewhere that
> developers can take advantage of ?
> 

Hmm, I'm not sure what you mean by locality of reference (I know it in the context of performance
optimizations)

But I have a feeling I know what you mean about state and documents.

Yes, there is another endpoint you can use, that gives you a comprehensive view of the state
at a database level.

The _changes feed is an http comet feed of updates as they occur on the database.

http://books.couchdb.org/relax/reference/change-notifications

Also, note that the map reduce view indexes are built from MVCC snapshots of the database,
so they are pure functional transforms of the database state as well.

Also note that the _show and _list functions are functional transforms from documents and
views, so they are also based strictly on the database state.

Hope that helps.

Chris

> Thanks in advance,
> 
> Bob


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