- Reference >
- mongo Shell Methods >
- Collection Methods >
- db.collection.dropIndex()
db.collection.dropIndex()¶
Definition¶
- db.collection.dropIndex(index)¶
Drops or removes the specified index from a collection. The db.collection.dropIndex() method provides a wrapper around the dropIndexes command.
注解
You cannot drop the default index on the _id field.
The db.collection.dropIndex() method takes the following parameter:
Parameter Type Description index string or document Specifies the index to drop. You can specify the index either by the index name or by the index specification document. [1]
To drop a text index, specify the index name.
To get the index name or the index specification document for the db.collection.dropIndex() method, use the db.collection.getIndexes() method.
Example¶
Consider a pets collection. Calling the getIndexes() method on the pets collection returns the following indexes:
[
{ "v" : 1,
"key" : { "_id" : 1 },
"ns" : "test.pets",
"name" : "_id_"
},
{
"v" : 1,
"key" : { "cat" : -1 },
"ns" : "test.pets",
"name" : "catIdx"
},
{
"v" : 1,
"key" : { "cat" : 1, "dog" : -1 },
"ns" : "test.pets",
"name" : "cat_1_dog_-1"
}
]
The single field index on the field cat has the user-specified name of catIdx [2] and the index specification document of { "cat" : -1 }.
To drop the index catIdx, you can use either the index name:
db.pets.dropIndex( "catIdx" )
Or you can use the index specification document { "cat" : -1 }:
db.pets.dropIndex( { "cat" : -1 } )
[1] | (1, 2) When using a mongo shell version earlier than 2.2.2, if you specified a name during the index creation, you must use the name to drop the index. |
[2] | During index creation, if the user does not specify an index name, the system generates the name by concatenating the index key field and value with an underscore, e.g. cat_1. |