MongoDB Interview Q & A

Last Updated: 04 August, 2023

What is the default port of MongoDB?

When a MongoDB Server instance is started on a machine, it has to start listening on a port. By default, port number 27017 is used to mongod and mongos instances.

What is “Namespace” in MongoDB?

The namespace is a combination of the database name and the name of the collection or index, like so: [database-name]. [collection-or-index-name] . All documents belong to a namespace. The maximum length of the collection namespace is 120 bytes.

How do I achieve primary key-foreign key relationships in MongoDB?

The primary key-foreign key relationship can be achieved by embedding one document inside another.

If we remove a document from the database, does MongoDB remove it from disk?

Yes, Removing a document from the database also removes it from the disk.

Why is MongoDB not recommended for a 32-bit system?

32-bit MongoDB processes are limited to about 2 GB of data since the MongoDB storage engine uses memory-mapped files for performance.

What is the maximum size of Index Key Limit and Number of Indexes per collection?

The total size of an index entry, which can include structural overhead depending on the BSON type, must be less than 1024 bytes. A single collection can have no more than 64 indexes.