20+ CouchDB Interview Questions

20+ CouchDB Interview Questions

CouchDB Interview Questions

1) What is CouchDB? 

CouchDB is archived database server available through a RESTful JSON API. It is dispersed, hearty, gradual replication with bi-heading. It is without blueprint with level location space.

CouchDB is an open source NoSQL database which centers around convenience. It was created by Apache. It is completely perfect with the web. CouchDB utilizes JSON to store information, JavaScript as its inquiry language to change the records, utilizing MapReduce, and HTTP for an API.

CouchDB highlights are as per the following:

CouchDB can be imitated over various server cases.

CouchDB has different libraries for your preferred language.

It has quick ordering and recovery

It has a REST-like interface for record addition, updates, recuperation, and cancellation.

CouchDB bolsters JSON-based record group, i.e., effectively translatable crosswise over various dialects.

Most recent discharge: Version 2.2.0 on Aug 8, 2018

2) In which language CouchDB is composed? 

CouchDB is written in Erlang. It is a simultaneous, useful programming language fundamentally centers around adaptation to internal failure (Erlang programming language likewise utilized for construct hugely versatile delicate continuous framework with prerequisites on high accessibility).

A portion of its parts are written in C language as well. As we realize that CouchDB bolsters see server and the perspectives (structure map or diminish) are written in JavaScript per default (however can likewise be written in Erlang). Thusly CouchDB requires the JavaScript motor SpiderMonkey (which is written in C language).

3) In which language CouchDB's initial work was begun? 

CouchDB early work was begun in C++. Be that as it may, later, it was supplanted by Erlang OTP stage.

Erlang has demonstrated as an incredible counterpart for this task.

4) How CouchDB is not quite the same as other SQL databases? 

CouchDB is certifiably not a social database. A few people feel that it is a substitution for a social database, yet it is totally not quite the same as SQL databases. It is quick, effective and shortcomings tolerant.

Love seat database SQL Databases

In CouchDB, JSON-based archive design are utilized to store information, JavaScript for MapReduce lists, and ordinary HTTP of its API.

Love seat database is a database which stores information in the JSON record. Question your file and records with the assistance of internet browser through HTTP. All the lists are consolidating with one another and change with the assistance of JavaScript. It is open source and uses RDBMS to store information. It is extremely quick, Multi-client, Multi-string, and vigorous SQL (organized inquiry language) database server.

SQL database for the most part utilized for huge information stockpiling of a vast undertaking.

It is a NoSQL database and preferences manual transmission. It is a SQL database and preferences programmed transmission.

Executed in Erlang programming language Implemented in C, C++ programming dialects.

Structure of NoSQL database:

CouchDB inquiries questions

5) Is CouchDB utilized in the Software business? 

CouchDB is exceptionally prominent now daily, and numerous organizations are utilizing CouchDB.

These are the basic highlights of CouchDB:

CouchDB can be repeated over different server cases.

CouchDB has different libraries for your preferred language.

It has quick ordering and recovery

It has a REST-like interface for archive addition, updates, recuperation, and erasure.

CouchDB underpins JSON-based record group, i.e., effectively translatable crosswise over various dialects.

That is the reason the product organizations use CouchDB.

Here we have a rundown of Top organizations which utilizes CouchDB:

Company Website Revenue Company size Country

GrubHub Inc. grubhub.com 200M-1000M 1000-5000 United States

Instigator Games, Inc. hotheadgames.com 10M-15M 50-200 Canada

Extreme programming bunch Inc. Ultimatesoftware.com 200M-1000M 1000-5000 United States

SLALOM,LLC Slalom.com 200M-1000M 5000-10000 United States

GenCorp technologies Credera.com 10M-50M 200-500 United States

6) What is the distinction among CouchDB and MongoDB? 

These are the accompanying contrasts:

Criteria CouchDB MongoDB

Interface REST/HTTP TCP/IP Custom Protocol

Article Storage Record is put away in records in the database. Record is put away in accumulations in the database.

Replication It pursues Master-Master replication. It pursues Master-Slave replication.

Question Method CouchDB pursues Map/Reduce inquiry technique. (JavaScript+others) MongoDB pursues Map/Reduce (JavaScript) making accumulation + object-based inquiry language.

Information Model It pursues the archive situated model and information is exhibited in JSON format. Document-Oriented (BSON)

Concurrency MVVC (Multi-rendition simultaneousness control). Update set up

Preference CouchDB favors availability MongoDB favors Consistency

Execution consistency In CouchDB, information is more secure than MongoDB In MongoDB, the database contains accumulations and gathering contains documents.It is quicker than CouchDB.

Composed in It is written in Erlang. It is written in C++.

MongoDB is quicker than CouchDB, and versatility is likewise better of the MongoDB.

CouchDB keeps running on various working framework like Android, iOS stage however MongoDB doesn't bolster versatile OS. Mongo DB is better as contrast with CouchDB for fast development when the structure isn't plainly characterized from the earliest starting point.

7) What is the comparability among MongoDB and CouchDB? 

The comparability among MongoDB and CouchDB are:

MongoDB and CouchDB both are the record arranged databases.

MongoDB and CouchDB both are the best instances of an open-source NoSQL database. i.e., both are without schema.

MongoDB and CouchDB both help JavaScript, can be utilized in questions, bolster accumulation capacities, for example, MapReduce and sent the database to execute it.

MongoDB and CouchDB both help basic programming dialects C, C#, Erlang, Java, JavaScript, Ruby, Python, Haskell, PHP, Perl, Smalltalk, and so forth.

These are some normal usefulness of CouchDB and MongoDB.

8) What are the primary highlights of CouchDB? 

JSON Documents: CouchDB stores information in JSON record.

Soothing Interface: CouchDB does all assignments like replication, information addition, and so on by means of HTTP.

N-Master Replication: CouchDB encourages you to utilize a boundless measure of 'experts,' making for some fascinating replication topologies.

Worked for Offline: CouchDB can duplicate to gadgets (like Android telephones) that can go disconnected and handle information match up for you when the gadget is back on the web.

Replication Filters: CouchDB encourages you to channel decisively the information you wish to imitate to various hubs.

Corrosive semantics: The CouchDB document design pursues every one of the highlights of ACID properties. When the information is gone into the plate, it won't be overwritten. Archive refreshes (include, alter, erase) pursue Atomicity, i.e., they will be spared totally or not spared by any stretch of the imagination. The database won't have any in part spared or altered records. Practically these update are serialized, and any number of customers can peruse a record without pausing and without being intruded.

Archive stockpiling: CouchDB is a NoSQL database which pursues report stockpiling. Records are the essential unit of information where each field is exceptionally named and contains estimations of different information types, for example, content, number, Boolean, records, and so forth. Archives don't have a set breaking point to content size or component check.

In the long run consistency: CouchDB certifications to give accessibility and segment resilience.

Confirmation and Session Support: CouchDB encourages you to keep verification open through a session treat like a web application.

Security: CouchDB additionally gives database-level security. The authorizations per database are isolated into perusers and administrator. Perusers can both read and keep in touch with the database.

Approval: You can approve the embedded information into the database by joining with confirmation to guarantee the maker of the report is the person who is signed in.

Guide/Reduce List and Show: The fundamental explanation for the prevalence of MongoDB and CouchDB is map/decrease framework.

9) Why Does CouchDB not utilize Mnesia? 

There are numerous explanations for CouchDB not utilizing Mnesia:

It gives a capacity impediment of 2 gigs for each document.

It requires approval and fixup cycle after an accident or power disappointment, so regardless of whether the size impediment is lifted, the fixup time on extensive records is restrictive.

Mnesia has some helpful highlights, yet highlights of Mnesia aren't generally valuable for CouchDB.

Mnesia is anything but a broadly useful, expansive scale database. It works best as a setup type database.

Mnesia works best as a setup type database. It is essential for the ordinary tasks. The sort where the information isn't key to the capacity of the application, however vital for ordinary activity of it.

Things that need to refresh, design and frequently reconfigure like a system switch, HTTP intermediaries, and so on whose setup information is once in a while enormous.

10) How might you use exchanges with CouchDB? 

CouchDB utilizes a "Hopeful simultaneousness" display. In this model, in the event that you send a record form alongside your update, CouchDB rejects the change if the present archive rendition doesn't match to your sent update.

In this way, you need to re-outline numerous ordinary exchange based situations for CouchDB. It's useful to approach issues from a more elevated amount, as opposed to endeavoring to form Couch to a SQL based world.

In the event that you have a record depicting the thing, and it incorporates a field for "Amount accessible", you can deal with simultaneousness issues:

Most importantly recoup archive, note down property that sent by CouchDB alongside database, from that point onward, Decrement the amount field, if it's more prominent than zero. From that point onward, send the refreshed report back utilizing the _rev property. Check, If the _rev matches the right now put away number, be done else in the event that there is a contention when _rev isn't coordinated, at that point recuperate the most up to date archive variant.

For instance:

I might want to take an ("ace item") report that contains every one of the information data like name, picture portrayal, cost, and so forth.
11) As CouchDB is written in Erlang and Erlang is known as moderate to embrace Unicode. Things being what they are, on the off chance that it makes an issue for CouchDB?

CouchDB utilizes Erlang twofold inside. Thus, information come to CouchDB is dependably UTF-8 encoded. There is no issue happened.

12) What is the use of CouchDB? 

CouchDB encourages designers to compose a customer side application which connects straightforwardly to the Couch without the need of server-side center layer. It decreases the season of improvement and taking care of replication. Its database is put away locally so the application can run no dormancy. The principle target of CouchDB is to keep running on the web applications and the associated gadgets through which we get to the web.

CouchDB has a HTTP-based REST API, which makes correspondence with the database extremely simple.

CouchDB has the straightforward structure of HTTP assets and techniques (GET, PUT, and DELETE) that are straightforward and use.

In CouchDB, information is put away in the adaptable archive based structure in this way, there is no compelling reason to stress over the structure of the information.

CouchDB encourages clients with amazing information mapping, which permits questioning, joining, and sifting the data.

CouchDB gives simple to-utilize replication, utilizing which you can duplicate, share, and synchronize the information among databases and machines.

13) What do you think about couchdbKit? 

The couchdbKit gives a system to your Python application to get to and oversee Python applications. It offers highlights to effectively get to and oversee CouchDB by a customer, permit to oversee databases, Couch database server, doc the executives, and view get to.

Articles generally reflect python object for administration. Server and information items could be utilized for instance.

Ventures to introduce couchdbkit:

Couchdbkit requires python 2.x better than 2.6

To introduce Couchdbkit utilizing pip you should ensure that you have an ongoing form on convey introduced.

$ twist - 0 http://python-distribute.org/distribute_setup.py

$ twist sudo python distribute_setup.py

$ easy_install pip

To introduce or move up to a most recent discharged form of couchdbkit

$ pip introduce couchdbkit

14) Can Views update records or databases? 

No. Perspectives are dependably perused just for databases and their records.

Perspectives are utilized for the accompanying reason:

It channels the record from the database to discover pertinent information for a specific procedure.

Extricating information from archives and present it in a particular request.

Building lists to discover the archive by any esteem or structure that lives in them and utilize these lists to speak to the connection between records.

At last, with perspectives, you can make a wide range of computations on the information in your reports

For instance:

In the event that archives speak to your organization's money related exchanges, a view can respond to the topic of what the spending was in the most recent week, month, or year.

15) What stages are upheld in CouchDB? 

Most POSIX frameworks are upheld like GNU/Linux and OS X. Window isn't authoritatively bolstered however it should work.

16) What is the utilization of groupings? How would you do arrangements? 

Successions are frequently used to guarantee interesting identifiers for each column in a database table. Successions are difficult to acknowledge with replication. CouchDB creates exceptional ids from its own, and you can indicate your very own also, so you needn't bother with an arrangement here. On the off chance that you utilize an arrangement for something different, you may figure out how to express in CouchDB in another way.

17) How would you be able to do replication? 

Replication: Replication synchronizes two duplicates of a similar database; these databases live on a similar server or can be live on two distinct servers. On the off chance that you change one duplicate of the database, replication will send the subtleties to another duplicate.

For replication, first you need to send solicitation of HTTP to CouchDB with a source, and an objective database and CouchDB will send the progressions from source to target.

How about we see, what replication looks like:

POST/_replicate with a post group of




Here $source_database and $target_database can be the names of nearby database or full URIs of remote databases. The two databases should be made before they can be duplicated from or to.

18) Is it conceivable to convey to CouchDB without experiencing HTTP/API? 

CouchDB's information demonstrate and inner API map the REST/HTTP display in a straightforward manner that some other API would acquire a few highlights of HTTP. Nonetheless, there is an arrangement to refractor CouchDB's internals to give an archived Erlang API.