reIndex on MongoDB

db.collection.reIndex()

Reindex all mongodb collections

db.getCollectionNames().forEach(function(coll_name) {
  var coll = db.getCollection(coll_name);
  coll.reIndex();
});

References
https://docs.mongodb.com/manual/reference/method/db.collection.reIndex/#db-collection-reindex
https://stackoverflow.com/questions/12187225/command-to-reindex-all-mongodb-collections