MongoDB: db.collection. dropIndexes() method
db.collection.dropIndexes
The db.collection.dropIndexes() method is used to drop all indexes other than the required index on the _id field. Only call dropIndexes() as a method on a collection object.
Syntax:
db.collection.dropIndexes()
Example: MongoDB: db.collection.dropIndexes() method
Here we have create a duplicate of restaurants collection restaurants1 and the following indexes we have created on restaurants1 collection.
> db.restaurants1.getIndexes();
[
        {
                "v" : 1,
                "key" : {
                        "_id" : 1
                },
                "name" : "_id_",
                "ns" : "test.restaurants1"
        },
        {
                "v" : 1,
                "key" : {
                        "cuisine" : 1
                },
                "name" : "cuisine_1",
                "ns" : "test.restaurants1"
        },
        {
                "v" : 1,
                "key" : {
                        "cuisine" : 1,
                        "address.zipcode" : -1
                },
                "name" : "cuisine_1_address.zipcode_-1",
                "ns" : "test.restaurants1"
        }
]
The single field index on the fieldcuisinehas the user-specified name ofcuisine_1and the index specification document of{"cuisine":1} and a compound index on thecuisinefield (in ascending order) and the zipcodefield (in descending order.).
Now, the following statement will drop all the indexes from restaurants1 collection.
db.restaurants1.dropIndexes();
Here is the output
{
        "nIndexesWas" : 2,
        "msg" : "non-_id indexes dropped for collection",
        "ok" : 1
}
Now, lists the indexes again.
> db.restaurants1.getIndexes();
[
        {
                "v" : 1,
                "key" : {
                        "_id" : 1
                },
                "name" : "_id_",
                "ns" : "test.restaurants1"
        }
]
Retrieve the restaurants data from here
Previous:
 db.collection.dropIndex() method
Next: 
 db.collection.explain() method
