Introduction to MongoDB collection.estimatedDocumentCount() Method

MongoDB is a popular NoSQL database that can handle massive amounts of data efficiently. In MongoDB, the estimatedDocumentCount() method is used to estimate the number of documents in a collection, which can improve query performance when dealing with large datasets.

Syntax

The syntax of the estimatedDocumentCount() method is as follows:

db.collection.estimatedDocumentCount()

Here, collection is the name of the collection.

Use cases

The estimatedDocumentCount() method is suitable for scenarios where you need to query the number of documents in a collection, especially when the number of documents is very large. This method uses a lightweight estimation algorithm to quickly calculate the number of documents without scanning the entire collection.

Examples

Here are two examples of using the estimatedDocumentCount() method.

Example 1

Assume we have a collection named users that contains a large number of user information documents. We can use the following code to estimate the number of documents in the collection:

> db.users.estimatedDocumentCount()
1000000

This means that there are 1,000,000 documents in the collection.

Example 2

Assume we have a collection named orders that contains a large number of order information documents. We can use the following code to estimate the number of documents in the collection:

> db.orders.estimatedDocumentCount()
5000000

This means that there are 5,000,000 documents in the collection.

Conclusion

The estimatedDocumentCount() method is an efficient way to estimate the number of documents in a collection. It is suitable for scenarios where large datasets need to be processed, and it can quickly calculate the number of documents without scanning the entire collection.