Create compound index mongodb

Aggregation pipeline example db.orders.aggregate([{$match:{status:'paid'}},{$group:{_id:'$userId',total:{$sum:'$amount'}}},{$sort:{total:-1}},{$limit:10}]) Check replication lag rs.printSecondaryReplicationInfo() Current operations (slow queries) db.currentOp({active:true, secs_running:{$gt:5}}) Dump a database mongodump --uri='mongodb://localhost:27017' --db=mydb --out=/backup/$(date +%F) Replica set status mongosh --eval 'rs.status().members.forEach(m=>print(m.name,m.stateStr,m.optimeDate))'