Optimizer plan EXPLAIN

Explain:

***********query planner******************

db.example.explain().find({a:17}).sort({b:-1})

- Stage tells "collscan" or "Idxscan"

- Winning plan tells which plan is choosen by this execution

db.example.explain().remove({a:17,b:12})

- Taking explain plan for removing indexes


*************executionStats*****************

Examing explain plan

exp=db.example.explain("executionStats")
Explainable(test.example)

exp.find({a:17,b:12})

This throw output with query planner section and exectuion stats which gives details how
itration time, number search, records returned, time to execute etc


*************allplansexecution*****************

expall=db.example.explain("allPlansExecution")

exp.find({a:17,b:12})

Examples:

db.sensor_readings.createIndex({active:1,tstamp:1})

db.products.createIndex({for:1})

db.products.find({for:"ac3"})

db.products.explain().find({for:"ac3"})

exp=db.products.explain("executionStats")

exp.find({for:"ac3"})