MongoDB maxIdleTimeMS – How to Set via Command Line or Mongo Shell

Your query is using the index to fetch the results but needs to sort them afterwards which is an expensive operation.

"scanAndOrder" : true, scanAndOrder is a boolean that is true when the query cannot use the order of documents in the index for returning sorted results: MongoDB must sort the documents after it receives the documents from a cursor.

The solution is to apply an index on {imei:1, type:1, time:-1} or {type:1, imei:1, time:-1} (the imei,type order on the index depends on imei and type selectivity)

To see if the hardware is not limiting:

• top/htop => cpu percentage
• iostat -x 1 => sysstat tool to see disk r/w limits (%util)

Concerning locking:

• Mongo 2.6 : database locking
• Mongo 3.0 + MMAPv1 storage engine : collection locking
• Mongo 3.0 + WiredTiger storage engine : document locking

If you have 1 huge collection (server-prod), maybe Sharding is an option to distribute the load, or more cores + less locking with Mongo3.0

Improve indexes: - More indexes = slower write + faster read - Less indexes = faster write + slower read

Read from Secondaries, Only write on Primary.

> db.setProvilingLevel(1,4)  ##  save slow logs for that db slower than 4ms
> db.system.profile.find({millis:{$gt:100}}).sort({ts:-1}) ## find queries slower than 100ms, order by timestamp descending
> ....query.explain()  ## find out which indexes it uses

Information: http://docs.mongodb.org/manual/administration/optimization/