Hi Chris, Thanks, that is a solution certainly but my app has millions of documents, even after reduction. I wouldn't want to page through them all very often. I need couchdb's ability to shake down only the items that have expired and efficiently maintain an up-to-date index. I need a view of a view!
Ben On Fri, Oct 31, 2008 at 8:07 AM, Chris Anderson <[EMAIL PROTECTED]> wrote: > On Thu, Oct 30, 2008 at 6:35 PM, Ben Nevile <[EMAIL PROTECTED]> wrote: > > > > So let's say we've implemented a word count. We have a nice view that is > > indexed by word, so we can query any word and find out how many times it > > appears. But if we want to know what words are the most frequent, seems > to > > me that currently we're out of luck. > > Ben, > > You're right that sorting on reduce values is not part of the current > feature set. Here is how I've done that work in the past: > > First, define just a map view, such that you'd like the reduce to be > performed on rows which have the same key. Then use the key_reduce > function from this code (or write your own) > > http://github.com/jchris/couchrest/tree/master/lib/couchrest/helper/pager.rb > > The idea is that this code pages through the view, yielding each key > and all of the values that are associated with it. You could do > whatever you like with this data. I define a "reduce" function in > ruby, and save it's output as documents in another database. Eg if > you're data is in my-db, then key_reduce into my-db-reduce. > > Then you can define another set of map (and/or reduce) views on > my-db-reduce, which will sort the keys by a reduce value. > > There are some missing features here. Chiefly this code is not all > that documented, and I'm certain parts of it could use more convention > and less ad-hoc decision making on the part of the user. But the > really big feature here would be incremental reduce. It's just a > matter of bookkeeping really, but it's not yet implemented. Perhaps > next time I have a novel use for key_reduce I'll get it working > incrementally. > > Hope this helps. > > > -- > Chris Anderson > http://jchris.mfdz.com >
