Mongo Index Analyser

Mongo Index Analyser is a tool to look though the mongo profile collection in order to analyse the use of indexes.

It can report the following information:

• The number of times each index is used in a query (sub-queries are counted individually)
• The queries that were executed and did not use an index (either a COLLSCAN or a SORT occured)

Usage

First turn on profiling on your mongod instance from the mongo shell:

use somedatabase;
db.setProfilingLevel(2);

Then copy and paste the contents of indexStats.js into the shell and run

db.indexStats()

If you want to increase the size of the profile collection from its default which is small:

use yourdatabase;
db.setProfilingLevel(0);
db.system.profile.drop();
db.createCollection("system.profile", {capped: true, size: yourprofilesize})
db.setProfilingLevel(2);

On a replicaset you need to do setProfilingLevel on all members seperately, and they all log to their own profile collection (even though the drop/create commands are mirrored from the primary)

This was tested on mongo 3.0. Your mileage may vary on other versions, and generally :)