dropIndexes
dropIndexesThe
dropIndexescommand drops one or more indexes (except the index on the_idfield) from the specified collection.The command has the following form:
{ dropIndexes: <string>, index: <string|document|arrayofstrings>, writeConcern: <document>, comment: <any> } The command takes the following fields:
FieldTypeDescriptiondropIndexesStringThe name of the collection whose indexes to drop.indexstring or document or array of stringsThe index or indexes to drop.
To drop all but the _id index from the collection, specify
"*".To drop a single index, specify either the index name, the index specification document (unless the index is a text index), or an array of the index name. To drop a text index, specify the index names instead of the index specification document.
To drop multiple indexes (Available starting in MongoDB 4.2), specify an array of the index names.
writeConcerndocumentOptional. A document expressing the write concern of thedropcommand. Omit to use the default write concern.commentanyOptional. A user-provided comment to attach to this command. Once set, this comment appears alongside records of this command in the following locations:
mongod log messages, in the
attr.command.cursor.commentfield.Database profiler output, in the
command.commentfield.currentOpoutput, in thecommand.commentfield.
A comment can be any valid BSON type (string, integer, object, array, etc).
New in version 4.4.
Behavior
Starting in MongoDB 5.2, you can use dropIndexes 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.
Kill related queries only
Starting in MongoDB 4.2, the dropIndexes operation only kills
queries that are using the index being dropped. This may include
queries considering the index as part of
query planning.
Prior to MongoDB 4.2, dropping an index on a collection would kill all open queries on the collection.
Resource Locking
Changed in version 4.2.
dropIndexes obtains an exclusive lock on the specified collection
for the duration of the operation. All subsequent operations on the
collection must wait until dropIndexes releases the
lock.
Prior to MongoDB 4.2, dropIndexes obtained an exclusive
lock on the parent database, blocking all operations on the
database and all its collections until the operation completed.
Index Names
If the method is passed an array of index names that includes a non-existent index, the method errors without dropping any of the specified indexes.
_id Index
You cannot drop the default index on the _id field.
text Indexes
To drop a text index, specify the index name instead of the index specification document.
Stop In-Progress Index Builds
Starting in MongoDB 4.4, if an index specified to dropIndexes is still
building, dropIndexes attempts to stop the in-progress build. Stopping
an index build has the same effect as dropping the built index. In
versions earlier than MongoDB 4.4, dropIndexes returns an error if
there are any index builds in progress on the collection.
For replica sets, run dropIndexes 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
Starting in version 4.4, MongoDB adds the ability to hide or unhide indexes from the query planner. By hiding an index from the planner, users 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, the user 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.
Examples
To drop all non-
_idindexes , specify"*"for theindex(See Indexes Named*).db.runCommand( { dropIndexes: "collection", index: "*" } ) To drop a single index, issue the command by specifying the name of the index you want to drop. For example, to drop the index named
age_1, use the following command:db.runCommand( { dropIndexes: "collection", index: "age_1" }) mongoshprovides the helper methodsdb.collection.dropIndex()anddb.collection.dropIndexes():db.collection.dropIndex("age_1"); To drop multiple indexes, issue the command by specifying an array of the index names:
db.runCommand( { dropIndexes: "collection", index: [ "age_1", "age_1_status_1" ] } )