In MongoDB, the hideIndex
operation is used to hide an index from the query planner. This method is essential for testing the impact of index usage on query performance within MongoDB collections.
db.collection.hideIndex(indexName)
The hideIndex
method takes an indexName
parameter to specify the name of the index to hide.
Let's look at an example of how to use the hideIndex
method in the programGuru
collection in MongoDB:
db.programGuru.hideIndex("name_index")
This command hides the index named name_index
from the query planner in the programGuru
collection.
Let's go through a complete example that includes switching to a database, creating a collection, creating indexes, and hiding an index.
This step involves switching to a database named myDatabase
.
use myDatabase
In this example, we switch to the myDatabase
database.
This step involves creating a new collection named programGuru
in the myDatabase
database.
db.createCollection("programGuru")
Here, we create a collection named programGuru
.
This step involves inserting documents into the programGuru
collection.
db.programGuru.insertMany([
{ name: "John Doe", age: 30, email: "john.doe@example.com" },
{ name: "Jane Smith", age: 25, email: "jane.smith@example.com" },
{ name: "Jim Brown", age: 35, email: "jim.brown@example.com" }
])
We insert multiple documents into the programGuru
collection.
This step involves creating indexes in the programGuru
collection.
db.programGuru.createIndexes([
{ key: { name: 1 }, name: "name_index" },
{ key: { age: -1 }, name: "age_index" },
{ key: { email: 1 }, name: "email_index", unique: true }
])
We create three indexes: an ascending index on the name
field, a descending index on the age
field, and a unique index on the email
field.
This step involves using the hideIndex
method to hide an index from the query planner in the programGuru
collection.
db.programGuru.hideIndex("name_index")
We hide the index named name_index
from the query planner.
The MongoDB hideIndex
operation is crucial for testing the impact of index usage on query performance. Understanding how to use this method allows you to efficiently manage and optimize the performance of your MongoDB collections.