CouchDB Ranking

Question

I'm trying to figure out the best way of sorting by rank using couch db. I have my documents setup in a players db like so:

{
   "_id": "user2",
   "_rev": "31-65e0e5bb1eba8d6a882aad29b63615a7",
   "username": "testName",
   "apps": {
       "app1": {
           "score": 1000
       },
       "app2": {
           "score": 1000
       },
       "app3": {
           "score": 1000
       }
   }
}

The player can have multiple scores for various apps. I'm trying to figure out the best way to pull say the top 50 scores for app1.

score 2 · Accepted Answer · edited May 23 '17 at 11:57

2

I think one idea could be to store the score of each user for each app seperately. Like so: -

{"app":"app1","user":"user_id","score":"9000"}

The you could write a map function

emit([doc.app,doc.score],{_id:doc.user,score:doc.score})

and query the view like

/view_name?include_docs=true&startkey=["app1",{}]&endkey=["app1"]&descending=true

With this arrangement you have a view sorted by the score and the name of the app. Here are the results that you get.

{"total_rows":2,"offset":0,"rows":[

{"id":"61181c784df9e2db5cbb7837903b63f5","key":["app1",10000],"value":

{"_id":"5002539daa85a05d3fab16158a7861c1","score":10000},"doc": {"_id":"5002539daa85a05d3fab16158a7861c1","_rev":"1-8441f2f5dbaaf22add8969cea5d83e1b","user":"jiwan"}},

{"id":"7f5d53b2da8ae3bea8e2b7ec74020526","key":["app1",9000],"value":

{"_id":"336c2619b052b04992947976095f56b0","score":9000},"doc": {"_id":"336c2619b052b04992947976095f56b0","_rev":"3-3e4121c1831d7ecafc056e71a2502f3a","user":"akshat"}} ]}

You have score in value. User in doc.

Edit

Oops! I mistyped the startkey and endkey :) Notice that it is not startKey but startkey same for endkey. Also note that since descending is true we reverse the order of keys. It should work as expected now.

For more help check out

This answer and
This answer

edited May 23 '17 at 11:57

Community

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answered Jul 07 '14 at 04:13

Akshat Jiwan Sharma

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Thanks so much this was a huge help. I wasn't able to get your url working as it would add all the documents and not just app1 documents. So I removed the startkey and endkey and replaced it with just key and that did the trick. /view_name?key="app1"&descending=true – Dave Jul 07 '14 at 06:23
Hey Dave that was a typo in my answer. Sorry about that :) check my edited answer the key ranges should be working now. – Akshat Jiwan Sharma Jul 07 '14 at 06:52
1

Thanks a ton I was able to get everything working. I just started using couchdb yesterday and swtiching from mysql I was loosing my mind. Your post made it a lot easier to kind of tie everything I read online to actual code. I now have a much better understanding of views, key=>value etc etc. – Dave Jul 07 '14 at 07:56
Glad I could help :) And considering you started couchdb just yesterday I think you have covered lot's of ground. Hope your time with couchdb is relaxing! (could not help myself there ha ha) – Akshat Jiwan Sharma Jul 07 '14 at 07:59

CouchDB Ranking

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