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Mongodb indexes will improve the efficiency of data query in collections most of the time. However, multiple indexes for query fields may cause Mongodb to select the wrong index, which will have a negative impact on query efficiency. At the same time, database administrators also need to check the usage of indexes regularly and clean up unused indexes to reduce the impact on data insertion and updating. When the wrong name is entered during index construction or the index is renamed, the index also needs to be deleted.

This article organizes official documents and introduces how to delete Mongodb indexes.

How to delete an index

Deleting an index

db.collection.dropIndex()

Deleting multiple indexes

db.collection.dropIndexes()

If the user does not specify an index name array, delete all indexes except the _id field. If the user specifies an index name array, delete the array according to the array name specified by the user.

Precautions

• When the user wants to delete the _id field index, the collection needs to be deleted.
• When users delete indexes, the query performance of the application may be affected. Therefore, MongoDB recommends hiding the index first and deleting it only when it is determined that it will not have a significant impact on the application.

application

Use the getIndexes() method to get the index name.

db.collection.getIndexes()

Deleting a single index

db.collection.dropIndex("<indexName>")

Deleting multiple indexes

db.collection.dropIndexes(["<indexName1>","<indexName1>",...])

Delete all indexes except the _id index

db.collection.dropIndexes()

After deleting, use getIndexes() to view the index

db.collection.getIndexes()