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From: Zachary Zolton <zachary.zolton@gmail.com>
Date: Fri, 5 Jun 2009 09:13:19 -0500
Message-ID: <f728979f0906050713u743481efk5c60a160fa35e9d2@mail.gmail.com>
Subject: Re: chaining map reduce in hovercraft
To: dev@couchdb.apache.org
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So, Chris, it sounds like you're saying that POSTing to that URL will
place the entire results of querying the view with group=true into
another database. Sounds great!

Will it work with 0.9? Would you suggest automating this using _changes?

Cheers,
Zach

On Fri, Jun 5, 2009 at 6:17 AM, Viacheslav Seledkin
<viacheslav.seledkin@avicomp.com> wrote:
> 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?
>