db.collection.dropIndex()
On this page
Definition
db.collection.dropIndex(index)
Important
mongosh Method
This page documents a
mongosh
method. This is not the documentation for database commands or language-specific drivers, such as Node.js.For the database command, see the
dropIndexes
command.For MongoDB API drivers, refer to the language-specific MongoDB driver documentation.
Drops or removes the specified index from a collection.
Note
You cannot drop the default index on the
_id
field.You cannot specify
db.collection.dropIndex("*")
to drop all non-_id
indexes. Usedb.collection.dropIndexes()
instead.
To get the index name or the index specification document for the
db.collection.dropIndex()
method, use thedb.collection.getIndexes()
method.The
db.collection.dropIndex()
method takes the following parameter:ParameterTypeDescriptionindex
string or documentOptional. Specifies the index to drop. You can specify the index either by the index name or by the index specification document.
To drop a text index, specify the index name.
You cannot specify
"*"
to drop all non-_id
indexes. Usedb.collection.dropIndexes()
instead.If an index specified to
db.collection.dropIndex()
is still building,db.collection.dropIndex()
attempts to stop the in-progress build. Stopping an index build has the same effect as dropping the built index. See Stop In-Progress Index Builds for more complete documentation.
Behavior
Starting in MongoDB 5.2, you can use db.collection.dropIndex()
to drop existing
indexes on the same collection even if there is a build in progress on
another index. In earlier versions, attempting to drop a different
index during an in-progress index build results in a
BackgroundOperationInProgressForNamespace
error.
Resource Locking
db.collection.dropIndex()
obtains an exclusive lock on the specified collection
for the duration of the operation. All subsequent operations on the
collection must wait until db.collection.dropIndex()
releases the
lock.
Stop In-Progress Index Builds
If an index specified to db.collection.dropIndex()
is still building, db.collection.dropIndex()
attempts
to stop the in-progress build. Stopping an index build has the same effect as
dropping the built index.
For replica sets, run db.collection.dropIndex()
on the primary.
The primary stops the index build and creates an associated
"abortIndexBuild" oplog entry. Secondaries which replicate
the "abortIndexBuild" oplog entry stop the in-progress index build and
discard the build job. See Index Build Process for detailed
documentation on the index build process.
Use currentOp
to identify the index builds associated with
a createIndexes
or db.collection.createIndexes()
operation. See Active Indexing Operations for an example.
Hidden Indexes
MongoDB offers the ability to hide or unhide indexes from the query planner. By hiding an index from the planner, you can evaluate the potential impact of dropping an index without actually dropping the index.
If after the evaluation, the user decides to drop the index, you can drop the hidden index; i.e. you do not need to unhide it first to drop it.
If, however, the impact is negative, the user can unhide the index instead of having to recreate a dropped index. And because indexes are fully maintained while hidden, the indexes are immediately available for use once unhidden.
For more information on hidden indexes, see Hidden Indexes.
Example
Consider a pets
collection. Calling the
db.collection.getIndexes()
method on the pets
collection
returns the following indexes:
[ { "v" : 2, "key" : { "_id" : 1 }, "name" : "_id_" }, { "v" : 2, "key" : { "cat" : -1 }, "name" : "catIdx" }, { "v" : 2, "key" : { "cat" : 1, "dog" : -1 }, "name" : "cat_1_dog_-1" } ]
The single field index on the field cat
has the user-specified name
of catIdx
[1] 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] | 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 . |