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From Antony Blakey <>
Subject Re: Architectural advice requested, and some 1.0 suggestions.
Date Thu, 06 Nov 2008 05:03:15 GMT

On 06/11/2008, at 3:15 PM, Paul Davis wrote:

> When we index outside of erlang, we don't have the consistent
> read-state guarantee if we page through the _all_docs_by_seq view as
> per usual design pattern. We could read the entire thing view into
> memory, but that has the obvious not-scalable side effect. Thus by
> default all external indexers (external == accessing couchdb via http)
> would have the second form of updating until they reach a steady
> state. This in deed could lead to race conditions with an indexer
> never managing to stay quite in sync.

Yet another reason to write a plugin rather than a loosely coupled  
_external, and use a core equivalent to an _all_docs_by_seq iterator  
that gives a consistent snapshot.

> As for the specifics of mnesia vs. sqlite I couldn't tell you. My
> guess is that the mnesia integration would kick the crap out of the
> sqlite integeration seeing as mnesia is part of the core library. But
> you mentioned GIS stuff and I haven't a clue on mnesia support for
> such things. Also, mnesia has that whole horizontal scale thing baked
> in.

I'm not interested in GIS, I just used GeoCouch as an example of an  
external indexer. I think Mnesia will do what I want for indexing.


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

The fact that an opinion has been widely held is no evidence whatever  
that it is not utterly absurd.
   -- Bertrand Russell

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