db.collection.reIndex()

• db.collection.reIndex()

mongo Shell Method

This page documents the mongo shell method, and doesnot refer to the MongoDB Node.js driver (or any other driver)method. For corresponding MongoDB driver API, refer to your specificMongoDB driver documentation instead.

The db.collection.reIndex() drops all indexes on acollection and recreates them. This operation may be expensive forcollections that have a large amount of data and/or a large numberof indexes.

Warning

• For most users, the db.collection.reIndex() operationis unnecessary.

• Avoid running db.collection.reIndex() against acollection in a replica set.

• Do not run db.collection.reIndex() against acollection in a sharded cluster.

Changed in version 4.2: MongoDB disallows db.collection.reIndex() to berun on a mongos, implementing a strongerrestriction against runningdb.collection.reIndex() for a collection in asharded cluster.

Behavior

Note

For replica sets, db.collection.reIndex() will not propagate from theprimary to secondaries. db.collection.reIndex() willonly affect a single mongod instance.

Important

Starting in MongoDB 4.0, db.collection.reIndex() takes a globalexclusive (W) lock and blocks other operations on thedatabase and all its collections until it finishes.

• For MongoDB 2.6 through MongoDB versions withfeatureCompatibilityVersion (fCV) set to "4.0"or earlier, MongoDB will not create an index on a collection ifthe index entry for an existing document exceeds the Maximum Index Key Length.

See also

Indexes