Mongo optimization

https://docs.mongodb.com/manual/administration/monitoring/

// all queries that do a COLLSCAN
db.system.profile.find({"planSummary":{$eq:"COLLSCAN"},
"op" : {$eq:"query"}}).sort({millis:-1})

// 5 secs more
db.currentOp().inprog.forEach(
  function(op) {
    if(op.secs_running > 5) printjson(op);
  }
)

// any query or command doing range or full scans
db.system.profile.find({"nreturned":{$gt:1}})

// top ten slowest queries
db.system.profile.find({"op" : {$eq:"query"}}, {
"query" : NumberInt(1),
"millis": NumberInt(1)
}
).sort({millis:-1},{$limit:10}).pretty()

//find all queries that take more than ten milliseconds, in descending order, 
displaying both queries and aggregations
db.system.profile.find({"millis":{$gt:10}}) .sort({millis:-1})