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From "Chris Anderson" <>
Subject Re: More on performance
Date Thu, 08 Jan 2009 21:46:20 GMT
On Thu, Jan 8, 2009 at 1:11 PM, Chris Van Pelt <> wrote:
> 1. Are the results of the reduce step stored to disk and pointed to by
> the index, or re-computed on every view request?

Generally, Couch avoids recomputation whenever possible. I think there
may be some opportunities to cache even more prior computations, but
generally, reduce uses cached results.

> 2. When new documents are added and the index recomputed, is the
> reduce step repeated for every document in the database?

No, just the intermediate values that are invalidated by the edit will
be recomputed. Generally, this should mean there are roughly O(log
N)+1 reduce calculations done per edited document, where N is the
total number of rows in the map. (I think I have my math right...)

> I love couch, and I'm really hoping I can bend it into my paradigm.  I
> can't find any other data store that has more promise.

Glad to hear, and can't wait to see what you do with it.

Chris Anderson

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