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From Viacheslav Seledkin <viacheslav.seled...@avicomp.com>
Subject Re: chaining map reduce in hovercraft
Date Fri, 05 Jun 2009 11:17:23 GMT
Chris Anderson wrote:
> I finally got around to writing my map reduce copier. it's still
> basic, but what do you think?
>
> I want to put it into trunk as an http call, like:
>
> POST /_snapshot_view
>
> with JSON
>
> {"src":"/srcdb/_design/app/_view/reduce_count", "group_level":2,
> "target":"/targetdb"}
>
> Chainable map reduce seems to be one of the most popular requests on
> the survey we took, so hopefully this will make the heavy-data crew
> happy.
>
> There is an implementation here:
>
> http://github.com/jchris/hovercraft/commit/34b44527b660a740858cc71aa2c8326747465e31#L0R290
>
> What this does is take the results you'd get from query your reduce
> view with group=true, and copy them to a new database. Basically you
> end up with a database full of docs that look like:
>
> {
> "key":[2009,2,14],
> "value": 511
> }
>
> Since they are docs sitting in another CouchDB, you can use more
> ordinary CouchDB Map Reduce views on that database to do things like
> sort by value, so you can for instance sort tags by popularity, or
> days by user activity, etc.
>
> Chris
>
>
> --
> Chris Anderson
> http://jchrisa.net
> http://couch.io
>
> .
>
>   
The process of updating of shapshot db will be incremental?

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