MongoDB countDocuments()

In MongoDB the db.collection.countDocuments() method returns the count of documents that match the query for a collection or view.

The collection part is the name of the collection or view to perform the count operation on.

Read more

Copy/Clone a Database in MongoDB

In earlier versions of MongoDB, you could use the copyDB command or its helper method, db.copyDatabase() to copy a database.

MongoDB has since deprecated these. Also, starting in version 4.2, MongoDB has removed the copydb command, and therefore also the db.copyDatabase() method, which means that you can’t use them even if you wanted to if you’re using MongoDB 4.2 or later.

Fortunately, there’s another way to copy a MongoDB database.

Read more

Copy/Clone a Collection in MongoDB

In earlier versions of MongoDB, you could use the db.collection.copyTo() method to copy a collection.

MongoDB has since deprecated that method. Also, starting in version 4.2, MongoDB has removed the eval command. Given db.collection.copyTo() wraps eval, this means that you can’t use either of them if you’re using MongoDB 4.2 or later.

Fortunately, there’s another way to copy a MongoDB collection.

Read more

MongoDB distinct Command

In MongoDB, the distinct aggregation command finds the distinct values for a specified field across a single collection.

It returns a document that contains an array of the distinct values, as well as an embedded document with query statistics and the query plan.

Read more