DevOps 2021: Top 20 MongoDB Interview Questions for beginners
Basic MongoDB Interview Questions for beginners
1. What is MongoDB?
Ans:MongoDB is an open-source NoSQL, document database. It provides high availability, high performance, and easy scalability.
2. Explain ‘Namespace’ in MongoDB.
Ans: The process of concatenating the collection name and database name is called the Namespace. MongoDB stores the BSON objects in the collection.
3. What is meant by sharding in MongoDB?
Ans: The process of storing huge data across multiple machines is termed Sharding. Actually, it’s a MongoDB approach to satisfy the demands of data growth. The data partition of Sharding will be horizontal in a database/search engine. The partition of each data will be termed as shard and database shard.
4. How can you view the connection used by MongoDB?
Ans: To view the connection establishment by MongoDB, the following command will be used.
db_adminCommand(“connPoolStats”)
5. Explain the Replica set.
Ans: The group of Mongo instances can be called a Replica set which actually hosts the same data set. In this set, one node must be primary and others are secondary. From primary to secondary, all the nodes will replicate.
6. Write the syntax to create and drop the collection in MongoDB.
Ans: Syntax for creation of collection:
db.createCollection(name,options)
Syntax for dropping the collection:
db.collection.drop()
7.Explain the role of a profiler in MongoDB.
Ans: The roles and responsibilities of a MongoDB database profiler is used to display the performance characteristics of every operation against the database. The profiler is used to find the queries, which are slower than they should be.
8. What is the procedure to move the old files in the moveChunk directory?
Ans: We can move the old files in the moveChunk directory, during the normal shard balancing operation, the files are changed as backups and it will be deleted after the operations are done properly.
9. How can we provide safe backups in MongoDB?
Ans: To perform safe backups in MongoDB, Journaling is the key feature.
10. Mention, what is objectID composed of?
Ans: The objectID is composed of,
-
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- Timestamp
- Client Machine ID
- Client Process ID
- 3 byte incremented counter
11. What is the command syntax for inserting the document?
Ans: The syntax to insert the document is:
database.collection.insert(document).
12. How can you inspect the function of the document?
Ans: There is an efficient way to inspect the function of the document, without any parentheses, the function must be invoked.
13. Write the command to view the Mongo through a Link?
Ans: To view the Mongo by using the link, we need a command, db._adminCommand(“connPoolStats”)
14. Write the syntax to use an Index in MongoDB?
Ans: MongoDB provides an inbuilt method called createIndex() that allows user to create an index.
db.COLLECTION_NAME.ensureIndex ( {KEY:1} )
15. Explain what do you mean by GridFS in MongoDB.
Ans: GridFS is used for storing, retrieving an extensive amount of files such as Audio, Image, Video files. The GridFS possesses the default value to store the files as fs.files and fs.chunks to store the metadata in the file’s chunks.
16. Enlist the alternatives for MongoDB.
Ans: These are the most common and popular alternatives to MongoDB.
- Cassandra
- CouchDB
- Redis
- Riak
- HBase
17. Enlist the different languages that are supported by MongoDB.
Ans: MongoDB provides the official support for drivers of C, C++, C#, Java, Node.JS, Perl, PHP, Python, Ruby, Scala, Go, and Erlang.
18. Explain the structure of the objectID in MongoDB.
Ans: The objectID is BSON type,
- 4 bytes value representing seconds
- 3-byte machine identifier
- 2-byte process id
- 3 byte counter
19. What is an index in MongoDB?
Ans: An index in MongoDB is similar to how indexes work in other database systems. Indexes are applied at the collection level, and can store the value of a specific field or set of fields, ordered by the value of the field.
20. Does MongoDB support ACID transaction management and locking functionalities?
Ans: No. MongoDB does not support default multi-document ACID transactions. However, MongoDB provides atomic operation on a single document.
