51+ MongoDB Interview Questions

MongoDB Interview Questions

MongoDB Interview Questions

1) What do you comprehend by NoSQL databases? Is MongoDB a NoSQL database? clarify. 

Right now, the web is stacked with huge information, enormous clients, huge unpredictability and so on and furthermore ending up progressively complex step by step. NoSQL is answer of every one of these issues, It is certainly not a customary database the board framework, not by any means a social database the executives framework (RDBMS). NoSQL means "Not just SQL". NoSQL is a kind of database that can deal with and sort all kind of unstructured, muddled and confused information. It is only another approach to consider the database.

Indeed. MongoDB is a NoSQL database.

2) Which are the distinctive dialects bolstered by MongoDB? 

MonggoDB gives official driver backing to C, C++, C#, Java, Node.js, Perl, PHP, Python, Ruby, Scala, Go and Erlang.

You can utilize MongoDB with any of the above dialects. There are some other network upheld drivers as well yet the previously mentioned ones are formally given by MongoDB.

3) What are the diverse sorts of NoSQL databases? Give some precedent. 

NoSQL database can be delegated 4 essential sorts:

Key esteem store NoSQL database

Archive store NoSQL database

Section store NoSQL database

Chart base NoSQL databse

There are numerous NoSQL databases. MongoDB, Cassandra, CouchBD, Hypertable, Redis, Riak, Neo4j, HBASE, Couchbase, MemcacheDB, Voldemort, RevenDB and so on are the instances of NoSQL databases.

4) Is MongoDB superior to other SQL databases? In the event that truly, at that point how? 

MongoDB is superior to other SQL databases since it permits an exceptionally adaptable and versatile record structure.

For instance:

One information report in MongoDB can have five sections and the other one in a similar accumulation can have ten segments.

MongoDB database are quicker than SQL databases because of productive ordering and capacity systems.

5) What kind of DBMS is MongoDB? 

MongoDB is an archive arranged DBMS

6) What is the distinction among MongoDB and MySQL? 

Despite the fact that MongoDB and MySQL both are free and open source databases, there is a great deal of contrast between them in the term of information portrayal, relationship, exchange, questioning information, pattern plan and definition, execution speed, standardization and some more. To contrast MySQL and MongoDB resembles an examination among Relational and Non-social databases.

7) Why MongoDB is known as best NoSQL database? 

MongoDb is the best NoSQL database since, it is:

Record Oriented

Rich Query language


Profoundly Available

Effectively Scalable

8) Does MongoDB bolster essential key, remote key relationship? 

No. As a matter of course, MongoDB doesn't bolster essential key-outside key relationship.

9) Can you accomplish essential key - outside key connections in MongoDB? 

We can accomplish essential key-outside key relationship by implanting one report inside another. For instance: A location archive can be installed inside client record.

10) Does MongoDB need a ton of RAM? 

No. There is no need a ton of RAM to run MongoDB. It tends to be run even on a little measure of RAM since it progressively distributes and de-allots RAM as per the necessity of the procedures.

11) Explain the structure of ObjectID in MongoDB. 

ObjectID is a 12-byte BSON type. These are:

4 bytes esteem speaking to seconds

3 byte machine identifier

2 byte procedure id

3 byte counter

12) Is it genuine that MongoDB utilizes BSON to speak to archive structure? 


13) What are Indexes in MongoDB? 

In MondoDB, Indexes are utilized to execute inquiry effectively. Without lists, MongoDB must play out a gathering filter, for example examine each report in an accumulation, to choose those archives that coordinate the question explanation. On the off chance that a fitting list exists for an inquiry, MongoDB can utilize the file to restrict the quantity of reports it must review.

14) By default, which list is made by MongoDB for each accumulation? 

Naturally, the_id accumulation is made for each gathering by MongoDB.

15) What is a Namespace in MongoDB? 

Namespace is a connection of the database name and the accumulation name. Gathering, in which MongoDB stores BSON objects.

16) Can journaling highlights be utilized to perform safe hot reinforcements? 


17) Why does Profiler use in MongoDB? 

MongoDB utilizes a database profiler to perform qualities of every task against the database. You can utilize a profiler to discover questions and compose activities

18) If you evacuate an article trait, is it erased from the database? 

Truly, it be. Evacuate the property and afterward re-spare() the article.

19) In which language MongoDB is composed? 

MongoDB is composed and actualized in C++.

20) Does MongoDB need a ton space of Random Access Memory (RAM)? 

No. MongoDB can be kept running on little free space of RAM.

21) What language you can use with MongoDB? 

MongoDB customer drivers bolsters all the well known programming dialects so there is no issue of language, you can utilize any language that you need.

22) Does MongoDB database have tables for putting away records? 

No. Rather than tables, MongoDB utilizes "Accumulations" to store information.

23) Do the MongoDB databases have pattern? 

Indeed. MongoDB databases have dynamic pattern. There is no compelling reason to characterize the structure to make accumulations.

24) What is the technique to arrange the reserve estimate in MongoDB? 

MongoDB's reserve isn't configurable. In reality MongoDb utilizes all the free spaces on the framework naturally by method for memory mapped documents.

25) How to do Transaction/securing MongoDB? 

MongoDB doesn't utilize conventional locking or complex exchange with Rollback. MongoDB is intended to be light weighted, quick and unsurprising to its execution. It keeps exchange bolster easy to upgrade execution.

26) Why 32 bit rendition of MongoDB are not favored ? 

Since MongoDB utilizes memory mapped records so when you run a 32-bit work of MongoDB, the all out capacity size of server is 2 GB. However, when you run a 64-bit work of MongoDB, this gives basically boundless capacity estimate. So 64-bit is favored more than 32-bit.

27) Is it conceivable to expel old documents in the moveChunk catalog? 

Indeed, These documents can be erased once the tasks are done on the grounds that these records are made as reinforcements amid ordinary shard adjusting activity. This is a manual cleanup procedure and important to free up space.

28) What should do if a shard is down or moderate and you do an inquiry? 

In the event that a shard is down and you even do inquiry, at that point your question will be come back with a mistake except if you set an incomplete question choice. In any case, if a shard is moderate them Mongos will sit tight for them till reaction.

29)Explain the canvassed inquiry in MongoDB. 

An inquiry is called secured question if fulfills the accompanying two conditions:

The fields utilized in the question are a piece of a record utilized in the inquiry.

The fields returned in the outcomes are in a similar record.

30) What is the significance of secured inquiry? 

Secured inquiry makes the execution of the question quicker in light of the fact that records are put away in RAM or consecutively situated on plate. It makes the execution of the inquiry quicker.

Secured question makes the fields are canvassed in the list itself, MongoDB can coordinate the inquiry condition just as return the outcome fields utilizing a similar file without peering inside the reports.

31) What is sharding in MongoDB? 

In MongoDB, Sharding is a technique of putting away information records over different machines. It is a MongoDB way to deal with satisfy the needs of information development. It makes even parcel of information in a database or web search tool. Each segment is alluded as shard or database shard.

32) What is copy set in MongoDB? 

A copy can be determined as a gathering of mongo examples that have similar informational collection. In a reproduction set, one hub is essential, and another is optional. All information is recreated from essential to optional hubs.

33) What is essential and optional copy set in MongoDB? 

In MongoDB, essential hubs are the hub that can acknowledge compose. These are otherwise called ace hubs. The replication in MongoDB is single ace in this way, just a single hub can acknowledge compose tasks at once.

Auxiliary hubs are known as slave hubs. These are perused just hubs that imitate from the essential.

34) By default, which copy sets are utilized to compose information? 

Naturally, MongoDB composes information just to the essential reproduction set.

35) What is CRUD in MongoDB? 

MongoDB bolsters following CRUD tasks:





36) In which position MongoDB speaks to archive structure? 

MongoDB utilizes BSON to speak to record structures.

37) What will happen when you expel a record from database in MongoDB? Does MongoDB expel it from circle? 

Indeed. On the off chance that you expel a record from database, MongoDB will expel it from plate as well.

38) Why are MongoDB information documents substantial in size? 

MongoDB doesn't pursue record framework discontinuity and pre designates information documents to save space while setting up the server. That is the reason MongoDB information documents are substantial in size.

39) What is a capacity motor in MongoDB? 

A capacity motor is the piece of a database that is utilized to oversee how information is put away on circle.

For instance: one stockpiling motor may offer better execution for read-overwhelming outstanding tasks at hand, and another might bolster a higher-throughput for compose activities.

40) Which are the capacity motors utilized by MongoDB? 

MMAPv1 and WiredTiger are two stockpiling motor utilized by MongoDB.

41) What is the utilization of profiler in MongoDB? 

A database profiler is utilized to gather information about MongoDB compose tasks, cursors, database directions on a running mongod occurrence. You can empower profiling on a for every database or per-occurrence premise.

The database profiler composes every one of the information it gathers to the framework. profile accumulation, which is a topped gathering.

42) Is it conceivable to design the reserve measure for MMAPv1 in MongoDB? 

No. it is absurd to expect to design the reserve measure for MMAPv1 on the grounds that MMAPv1 does not permit arranging the store estimate.

43) How to arrange the reserve estimate for WiredTiger in MongoDB? 

For the WiredTiger stockpiling motor, you can indicate the greatest size of the reserve that WiredTiger will use for all information. This should be possible utilizing storage.wiredTiger.engineConfig.cacheSizeGB alternative.

44) How does MongoDB give simultaneousness? 

MongoDB utilizes peruser essayist locks for simultaneousness. Peruser author locks permit simultaneous perusers shared access to an asset, for example, a database or accumulation, yet give selective access to a solitary compose activity.

45) What is the distinction among MongoDB and Redis database? 

Distinction among MongoDB and Redis:

Redis is quicker than MongoDB.

Redis has a key-esteem stockpiling while MongoDB has an archive type stockpiling.

Redis is difficult to code yet MongoDB is simple.

46) What is the contrast among MongoDB and CouchDB? 

Contrast among MongoDB and CouchDB:

MongoDB is quicker than CouchDB while CouchDB is more secure than MongoDB.

Triggers are not accessible in MongoDB while triggers are accessible in CouchDB.

MongoDB serializes JSON information to BSON while CouchDB doesn't store information in JSON position.

47) What is the distinction among MongoDB and Cassandra? 

Distinction among MongoDB and Cassandra:

MongoDB is cross-stage archive situated database framework while Cassandra is elite appropriated database framework.

MongoDB is written in C++ while Cassandra is written in Java.

MongoDB is anything but difficult to regulate on account of disappointment while Cassandra furnishes high accessibility with no single purpose of disappointment.

48) Is there any need to make database direction in MongoDB? 

You don't have to make a database physically in MongoDB on the grounds that it makes automaically when you spare the incentive into the characterized gathering at first time.