Each index in the DDS uses a separate file for storage. If there are too many indexes in the database that are not in use or have duplicate functions, it will waste disk space to a certain extent and affect the write performance of the database.
For indexes with duplicate functions, such as the {"score": 1, "name": 1} composite index mentioned earlier, it can override the functionality of the {"score": 1} index.
Users can use mongo shell to connect to the document database instance, and then execute the following commands to check and clean it up.
To view the total size of all indexes for a table:
db.coll.totalIndexSize()
To view the size of each index:
db.coll.stats().indexSizes
To view the field and property information for each index:
db.coll.getIndexes()
To view the index creation time, usage count:
db.coll.aggregate([{$indexStats:{}}])To clean up the index:
db.coll.dropIndex({a: 1})