incubator-couchdb-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Chris Anderson" <jch...@grabb.it>
Subject Re: General-understanding questions about views
Date Sun, 29 Jun 2008 05:38:42 GMT
On Sat, Jun 28, 2008 at 9:17 PM, David King <dking@ketralnis.com> wrote:
> But in the example I gave (that I got from the CouchDB wiki), there's no way
> for the reduction to be accurate in the face of deletions and modifications
> without re-calculating it for every single item in the database. That is,
> given a database of 5 million rows, every time one is modified or deleted
> (or possibly even added, depending on implementation), all 5 million rows
> have to pass through that function
>

Now you're getting to the technical part. This quote from Damien is
the best I can do for you:

http://damienkatz.net/2008/02/incremental_map_1.html

... in this design, the reductions happen at index-update time, and
the reductions are stored directly inside the inner nodes of the view
b+tree index. Then at query time, the intermediate results are reduced
to their final result. The number of reductions that happen at query
time are logarithmic with respect to the number of matching
key/values.


-- 
Chris Anderson
http://jchris.mfdz.com

Mime
View raw message