Sorting CouchDB Views By Value

Question

I\'m testing out CouchDB to see how it could handle logging some search results. What I\'d like to do is produce a view where I can produce the top queries from the results

Answer 1

It is true that there is no dead-simple answer. There are several patterns however.

1. http://wiki.apache.org/couchdb/View_Snippets#Retrieve_the_top_N_tags. I do not personally like this because they acknowledge that it is a brittle solution, and the code is not relaxing-looking.

2. Avi's answer, which is to sort in-memory in your application.

3. couchdb-lucene which it seems everybody finds themselves needing eventually!

4. What I like is what Chris said in Avi's quote. Relax. In CouchDB, databases are lightweight and excel at giving you a unique perspective of your data. These days, the buzz is all about filtered replication which is all about slicing out subsets of your data to put in a separate DB.

   Anyway, the basics are simple. You take your .rows from the view output and you insert it into a separate DB which simply emits keyed on the count. An additional trick is to write a very simple _list function. Lists "render" the raw couch output into different formats. Your _list function should output

   { "docs":
       [ {..view row1...},
         {..view row2...},
         {..etc...}
       ]
   }
   

   What that will do is format the view output exactly the way the _bulk_docs API requires it. Now you can pipe curl directly into another curl:

   curl host:5984/db/_design/myapp/_list/bulkdocs_formatter/query_popularity \
    | curl -X POST host:5984/popularity_sorter/_design/myapp/_view/by_count
   

5. In fact, if your list function can handle all the docs, you may just have it sort them itself and return them to the client sorted.