MongoDB Interview Questions and Answers
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Best MongoDB Interview Questions and Answers
As we all know, nowadays MongoDB is highly preferred is most of the organizations. On making use of our top 50 MongoDB interview questions and answers, you can near success and acquire job at ease. Here you will find all sorts of MongoDB interview questions consists all range of questions from the basic to the advanced level. All these top 50 MongoDB interview questions and answers are prepared in prime consultation with the top recruiters in the industry. To attend the interview with maximum confidence and to acquire your dream job with maximum pay scale, just go through all the top 50 MongoDB interview questions and answers listed in our page.
These top 50 MongoDB interview questions and answers will be suitable for the aspirants like beginners and experienced professions who are willing to secure a perfect career in the field of MongoDB and to scale up their career progress. To prepare at ease for your MongoDB interview, make use of our curatively prepared top 50 MongoDB interview questions and answers. We wish you all success in your MongoDB interview. Prepare and conquer your dream career at ease.
The leading NoSQL database and a document oriented database that ensures maximum performance, availability and instant scalability is known as MongoDB.
MongoDB | Cassandra |
It ensures a document like data model | It provides a bigtable like data model |
Multi-indexed is used to query a data | Data querying can be made using scan or key |
Being the best NoSQL database, MongoDB is highly preferred because of the highlights mentioned below:
- It is a document oriented database
- It provides high performance
- It assures maximum availability
- MongoDB is highly scalable
- It can also act as the best query language
NoSQL database that stands for “Not Only SQL” provides exceptional mechanism and techniques which can be used to store and retrieve data that are required to fulfill the emerging needs of today’s applications which can also be used in some of the relational databases like Oracle and SQL.
Listed below are the types of NoSQL database:
- Document-oriented
- Key-Value Stores
- Graph Stores
- Wide-Column Stores
Few examples of NoSQL database are as follows:
- MongoDB
- Cassandra
- CouchDB
- HBASE
The main advantages of MongoDB are as follows:
- MongoDB is nothing but a Relational Database Management System (RDMS) that acts as a substitute for web applications providing partition tolerance mechanism to the users which RDMS cannot offer.
- MongoDB is also highly used for real-time analytics and assures maximum scalability which can be used to handle more complicated, unstructured and tangled data.
- Most of the organizations like Google, Nokia, Cisco, Facebook, Verizon and more are using MongoDB nowadays.
The major benefits of preferring MongoDB over other relevant programs are as follows:
- MongoDB is a highly scalable and flexible database structure than other programs
- MongoDB has specialized techniques to index and store data at ease
- MongoDB is also faster when compared to other programs
Listed below are some of the languages that can be used along with MongoDB:
- C
- C++
- C#
- Erlang
- Go
- Java
- js
- Perl
- PHP
- Python
- Ruby
- Scala
Some of the best features of MongoDB are as follows:
- Indexing
- Replication
- Ad-hoc queries
- Schemaless
- Sharding
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The profiler that comes with MongoDB consists of techniques which indicate the characteristics of the operations found in the database. It can also be used to analyze all the queries that are executed by the DB system. And, all the information can be utilized for examining when to call an index.
A combination of database and index or collection name is known as the namespace in MongoDB. For example: “game.cricket” where game is the database name and cricket is the collection or index name.
The technique with which you can store data over several machines is known as sharding in MongoDB. The method used for data storage is horizontal partitioning, it horizontally partitions the data present in the database or search engine and each of the partition can be defined as a shard or a database shard.
The instance group that hosts a similar set of data can be defined as a replica set. The two nodes available in replica set are primary and secondary in which the data from primary is replicated and shared with the secondary node.
Replication is the process that synchronizes data across multiple servers and that maximizes data availability and provides redundancy which prevents the database from single server loss. And, so in MongoDB replication can be used to assure instant recovery from hardware failures and service hindrance.
Every shard is actually a logical collection of partitioned data that comprises of a cluster of replicas or a single server. It is highly recommended to use replica set with every shard.
CRUD stands for Create, Read, and Update and Delete which are the basic operations of MongoDB.
In case the shard is down, you will get an error from the query until the “Partial” option of query is set. If the shard is slow, then the Mongos will wait until it performs.
The following components are present in the sharded cluster:
- Shards
- Query routers
- Config servers
The special structures of MongoDB that holds a small portion of the data set in an easy to traverse form is known as indexes in MongoDB.
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The main function of index is to ensure high performing read operations for the most continually utilized queries.
If the index is too large to fit in to the RAM, then MongoDB will read the index which is too quicker than reading RAM because index easily fits into the RAM if the server has got separate RAM for indexes in additional with the remaining sets.
These files are used only as backup while the normal shard operations are performed and so once the operation is finished, we can delete the files but this is manual and so we have to take care of removing the files in order to free up the space.
No, there is no need to clean up as the movement of chunk is actually continual and highly determined. The move will try and try until it is completed and the resultant data will be present only in the new shard.
In MongoDB safe backups can be performed using journaling.
While journaling is being executed, all the write operations are saved in the memory. The journal writes are habitual and so it is defined that all the on-disk journal files are dependable. The journal subdirectory present inside the dbPath is designed byMongoDB.
No, it cannot be replayed unless the entries are fully complete as every journal write is consistent.
Even though MongoDB, Couchbase and CouchbaseDB are identical in many techniques, there are also specific differences among them in the way of model execution, storage, crossing points, duplication and more.
Yes, it will be deleted and so it will be appreciable if you save the object again by eliminating the attribute.
GridFS in MongoDB is used to store and retrieve large files like video, audio and image files. To store the file’s metadata and chunks it makes use of the two files namely fs.files and fs.chunks.
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To ensure consistency, MongoDB utilizes reader-writer locks to permit readers to simultaneously access the collections or database but it always ensures private access to all single writes.
A part of the database that is used to manage data storage on the disk is known as the storage engine.
Actually, the writes or updates to disk are very slow and lazy by default, it takes almost a couple of seconds and so writes or update fsync to disk cannot be made immediately or instantly.
MongoDB is not preferred for 32 bit system because to run a 32 bit MongoDB along with the server, all the indexes and the information associated with it consumes about 2GB and so MongoDB is not preferred for 32 bit system.
The snapshot() method is highly used to isolate cursors from intervening with the specific write operations.
The operation that is used to process data records and return accurate computed results is known as aggregation in MongoDB.
Yes, null values are allowed only for the objects, it cannot be affixed with a database collection as it is not an object but {} can be affixed to it.
MongoDB aggressively allocates space in order to prevent data fragmentation and so the data files are too large.
db._adminCommand(“connPoolStats”); is the command with which the connections used by MongoDB can be viewed.
Objectld is made up of or it consists of the following:
- Timestamp
- Client machine ID
- Client process ID
- 3 byte incremented counter
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Save() is actually used to replace an existing document with a new, updated or the latest document.
MongoDB splitting is one of the background processes that prevent chunks from becoming larger.
Embedded document is used to convey the relationship existing among the data that are written inside the body and those documents can be received only when the data body is tiny.
No, MongoDB does not support the relationships of both foreign key and primary key by default.
The command that is used to furnish all the details of the query plan is explain() command.
To create a collection in MongoDB, db.createCollection (name, options) is used.
Mongorestore is the command used to restore the backup.
The backup of the database can be accessed or retrieved with the help of mongodump command.
The oplog actually records all the operations that are used to modify the data that are present in the replica set.
In order to display records in a formatted way, the pretty() method is used in MongoDB.
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