Introduction to MongoDB collection.unhideIndex() Method

MongoDB is a non-relational database that supports multiple data types and data structures. unhideIndex() is a method in MongoDB used to hide specified indexes in the database. By using this method, you can hide indexes without deleting them, to avoid them being mistakenly used.

Syntax

The syntax for the unhideIndex() method is as follows:

db.collection.unhideIndex(index)

Here, collection is the name of the collection where the index is to be hidden, and index is the name of the index to be hidden.

Use Cases

The unhideIndex() method is useful when you need to temporarily hide specific indexes in the database. For example, when you are performing data migration or performance testing, you can hide unnecessary indexes to improve query efficiency. Additionally, if you need to debug the usage of indexes, you can also use this method to control the display of indexes.

Example

Here is an example of using the unhideIndex() method to hide an index in a collection.

Assume we have a collection named students, which contains the following data:

{ name: "Alice", age: 25, gender: "F" }
{ name: "Bob", age: 30, gender: "M" }
{ name: "Charlie", age: 20, gender: "M" }

Create an index named nameIndex for the students collection:

db.students.createIndex({ name: 1 }, { name: "nameIndex" })

Now, we can use the unhideIndex() method to hide the index:

db.students.unhideIndex("nameIndex")

To display the index again, use the following method:

db.students.reIndex()

Conclusion

Through this article, we learned about the unhideIndex() method in MongoDB. By using this method, we can hide indexes without deleting them, to improve query efficiency or debug index usage.