Delete your Large MongoDB database effectively

You can use below javascript code to delete large database without having a long duration of global lock( which is blocked all other operations on this database, maybe your instance might get hang).

Initially, this script will delete all indexes belongs to the selected collection and then its' documents one by one. Once the collection has no documents, it drops the collection finally. Between these operations, sleep function is configured to avoid the global lock being held in longer duration.

var dbname= "dummy"
var URL = "localhost:27017/"+ dbname
db = connect(URL);

var collections = db.getCollectionNames();

for (var i in collections) {

        print ("Deleting collection : " + collections[i] +"...");
        print ("Droping all indexes in "+ collections[i] + "...");
        db[collections[i]].dropIndexes();
        sleep(5000);
        db[collections[i]].find().forEach(function(mydoc) {
                print ("Deleting document : " + mydoc._id)
                db[collections[i]].remove({'_id': mydoc._id})
                //print(mydoc.name);
                sleep(1000);
                }
        )
        db[collections[i]].drop();
        sleep(5000);
}

function sleep(milliseconds) {
  var start = new Date().getTime();
  while (new Date().getTime()< start + milliseconds)  {
    // Do nothing
  }
}