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Couchbase Interview Questions

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If you're looking for Couchbase Questions & Answers for Experienced or Freshers, you are at right place. There are lot of opportunities from many reputed companies in the world. According to research, average salary for CouchBase is approximately $122,071 pa. So, You still have opportunity to move ahead in your career in as CouchBase Administration. Mindmajix offers Advanced Couchbase Interview Questions 2018 that helps you in cracking your interview & acquire dream career as CouchBase Application Developer.
 

Q1) How can you say that a Couchbase Server is different from that of database software 

S.No Couchbase Server Other approaches
1 JSON documents can easily be stored                                                    JSON documents can be stored but there is a need to handle additional tasks for the same
2 Supports non- JSON documents too No support for non- JSON documents is available in most of the approaches
3 Binary data management is possible The same is not always possible
4 Vast support for API, REST and SQL is available No such support is available in all the cases


Q2) What exactly do you know about a Couchbase server?

A Cloudbase server is basically nothing but a NoSQL database which is faster, elastic, as well as easy to use. It is regarded as one of the finest oriented-database software package. The same is considered for the collective application that has multiple uses and are widely adopted in the modern day approaches. 

Related PagesIntroduction to Apache Cassandra NoSQL Database

Q3) Being an Open Source Technology, what are the other good things that you know about the Cloudbase?

In addition to open source technology, the Couchbase was released under Apache 2.0 license. It comes with a community and an enterprise edition. It has multiform capabilities that make it good enough to be considered for the long run.

Q4) What does N1Ql stands for?

It stands for non-first normal form query language

Q5) What do you know about a shared server and a dedicated server?

Organizations and businesses these days have the option to consider a server which is only dedicated to them. No other organization or business shares the same. On the other hand, a shred server is distributed among many businesses and it hosts a lot of businesses. The shared hosting has low price for obvious reasons as compared to a dedicated server. Both have their own pros and cons associated with each other. For businesses with small data needs and basic applications, the shared server is a good option to be considered. 

Q6) Do you think it’s vital to create a data bucket in the system? If so, why?

Yes, it is important. This is generally done because the server only prefers the data buckets when it comes to storing the data. When the server is installed, the default bucket gets created automatically. 

Q7) Can you name the two important functional blocks that are used in the Couchbase Server?

(OR)

What are the functional blocks involved in Couchbase Server?

Couchbase server involves two functional blocks. They are as follows:

1. Data Manager
2. Cluster Manager

Q8) What is data manager in the Couchbase Server?

It is actually a functional block with some useful applications. Actually, it is responsible for the purpose of extracting, as well as storing the data from the applications. There are certain other important tasks which it perform and without making an impact of the overall functionality of the software

Q9) Tell something about the Data Format in the Couchbase server?

The most basic unit of the data man manipulation in the Couchbase Server is a document. Documents get stored in the JSON document format without any predefined schemas.

(OR)

Generally, it depends on the data and its type. Most of the documents and the files are present in the basic format and there are no predefined schemas. The files can be located in the JSON format.

Q10) What do you know about the VBucket?

There are situations when the data needs to be divided or a portioning is performed in a logical manner. VBucket is an approach that is adopted for the same purpose. All the buckets present in the Couchbase get divided automatically if this option is enabled by the user. One of the best thing about this approach is the users can simply make sure of effective allocation of the data throughout a cluster.

(OR)

vBucket happens to be one of the logical ways of partitioning data due to the natural condition. It has been distributed over all the nodes in the clusters. The couchbase type bucket which gets designed in a group is split up automatically in a static group of slices. Then after, buckets map to the individual server. They are designed and used to assign information more effectively.

Q11) Can you tell something about the subsystems which are compatible with all the nodes in a network?

There are four subsystems that function on every node. They are as follows: 

1. Pattern Manager
2. Pulses
3. Single Ton Supervisor
4. Progression Monitor

The Singleton Supervisor makes sure to select the cluster head if there is an issue with the one already assigned. The Pulses make sure of regular exchange of data in the application that is mandatory to accomplish some important tasks. On the other hand, the Progression manager is the subsystem that is preferred to monitor the tasks going on. It also resumes the procedures that don’t get completed or are unsuccessful. The pattern manager is responsible mainly for the processing of local configuration.

Q12) What exactly does the Vbucket Map represents in the Couchbase?

(OR)

What do mean by vBucket Map and what does it represent?

The vBucket map happens to be responsible for representing the state of the cluster as soon as a running rebalance operation is completed. Rebalance Orchestrator is a process which correlates the target current maps in order to conclude to implement the movement of Tap Streams in order to create and administer. The Rebalance operation will then get exhaustive only when there are similar current and Target vBucket Maps.

(OR)

Generally, it is preferred when it comes to representing the state of a cluster. This is done post the completion of rebalance operation.  All the information regarding the same can easily be grabbed from the domain file present in the system. 

Q13) Tell something about the features of Couchbase you are familiar with?

There are certain features that make it simply the best. Couchbase is fast and known to process the complex requests in a very short span of time. The users need not to worry about the latency and the throughput. The overall cost that one needs to be invested on this is really low. Couchbase is simple to use and understand especially when it comes to installing, expanding, managing, as well as configuring for a basic change. The users don’t have to worry about anything when it comes to creating the schemas.

It is best when it comes to adapting the changes. All the minor and in fact, major changes can easily be adopted by this server in a very simple manner. The overall number of nodes can easily be extended without worrying about the performance. In addition to this, Couchbase is business-ready software and it can manage the critical applications. 

Q14) What is the strict upper limit on the storage capacity of a data bucket in Couchbase Server? Is it possible to extend the same?

Each data bucket is having a limit of 20MB. In case more storage is required, the same can be considered by talking the additional buckets into consideration. 

Q15) Name the elements which are present in Couchbase Node?

Every Couchbase Node contains four elements. The elements have been mentioned below point-wise.

1. Index Service
2. Data Service
3. Cluster Manager component
4. Query Service

Q16) Name the programming language which Cluster Manager uses?

Erlang Programming Language

Q17) What do you mean by the term data replication?

Replication is a term that defines that the same type of data is present at multiple locations in the server. The same can put unnecessary burden on the performance and sometime, it takes additional cost for the organization. 

Q18) What are the good reasons for you to consider the Couchbase Server?

There are certain good things about the Couchbase that makes it simply the best and there are tasks that can easily be accomplished through it. The very first thing is the maintenance which is very simple and users need not to worry about the same. Any sort of application even when they are different in features can be considered with it. The Couchbase is the server which simply makes sure consistency as well as control. In addition to this, flexibility and the scalability are the other factors responsible. The users are free to keep up the pace easily with the multiple use cases. Also, the biggest features of couchbase are the users can deploy several types of databases very easily. 

Q19) How the task of locating a document in the Couchbase can be made easy according to you?

By considering the JSON format, this task can be made very easy and the best part is the things are done in the rightful manner only through this approach. 

Q20) Name the ports that you can use when it comes to accepting or listening the requests?

(OR)

How many TCP ports are there to listen to the requests?

There are two TCP ports that are used to listen to requests.

1. Port 11210
2. Port 11211

The 11210 follows the cluster expansion rule while the Port 11211 follows the hashing algorithm

Q21) Tell something about the Cluster Manager in the Couchbase Server

It is mainly responsible for keeping an eye on the performance, as well as on the way the nodes are connected so a server. Depending on the tasks, there are certain types of methods through which the nodes can be connected to a server. It also makes sure that the code runs successfully on each lump. It also keeps a node reserved for the aggregation purpose.

Q22) What is Role-based access control authentication approach in the Couchbase?

Role-Based Access Control is capable enough of ensuring cluster-resources to gbe exclusively accessed by customers with suitable privileges. Talking about privileges, these are gathered in Couchbase-defined groups. Each set or group is associated with an individual role. Users are ensured to assign one or many roles, and the privileges are granted which are associated with every role.

(OR)

It simply makes sure that the cluster-resource can used only by those users which are authorized to do so. In the server, there are privileges are defined into different sets and these sets are often dedicated to some or one specific node. One user can have multiple roles and they are often granted the access for the privileges. 

Q23) In a database, how can you define a document?

It is nothing but a generally entry made to a database. A document can have a specific ID related to it and the same can be used for locating the document in the server. The real application data remains present in the document and the same can be accessed anytime by the user whenever the need of same is realized by the user. Documents also provide basic information about a specific task that is important. 

Q24) What are the chances of a Couchbase server failure and what are the factors that can be held responsible for the same?

The chances for the failure of a server are very less and the best thing is overall number of failures reported about Couchbase are very less. Some of the factors that can cause this issue are listed below

1. Failure of the power
2. No maintenance of the server
3. Presence of inauspicious data
4. Improper Integration
5. Hacking related issues
6. Slow bandwidth
7. Improper allocation of the same

Q25) What do you mean by the Cross Datacenter Replication?

XDCR or Cross Datacenter Replication helps in providing a seamless mode to replicate data from one set to another.Cross Datacenter Replication involves replicating activedata to N+1 Server clusters, or even external apps such as Spark, Elastic, Storm, and so forth. The sets are used for various geographical diverse data centers. They are used either for bringing data closer to customers for fast-paced data access or the recovery of any disaster.

(OR)

When it comes to replicating the data from one cluster to another, the cross datacenter replication is considered. When the datacenters are geographically different or when they are diverse, this approach is also considered for eliminating various problems from the domain.

Q26) What sort of technical specialty is required to handle the Couchbase or to work with the same?

Basic knowledge about the network and the computing is mandatory. Network communication basics, installation of the network and maintenance of the same are the other skills that are helpful. The other skills depend on the task assigned to you. 

Q27) What are the needs that the Couchbase Servers can easily satisfy?

There are certain needs that Couchbase server can easily fulfill. The first is assuring unified programming Interface can handle queries and search. In addition to this, mobile and Internet of Things demands can easily be fulfilled through this. Also, various tasks like core database engine, analytics, SQL integrations, scale-out architecture, core database engine, as well as memory first architecture can easily be fulfilled. 

Q28) How Couchbase Data Platforms are useful in building the applications that are scalable?

It provides uniform, simple, quick and in fact a powerful application development API which always make sure of applications that are good enough to be considered. As it can easily be deployed, the application needs can be fulfilled in a very short span of time. Intelligence can easily be added to the applications, time delays can be avoided and the overall downtime can be reduced upto a great extent.

Q29) What are the capabilities of a core database engine?

There are certain abilities of the same which is very useful when it comes to managing the data of the applications. In addition to this, it is also good enough to be trusted for the document applications. The users can easily deploy its architecture anywhere they want. Other capabilities include caching of data, data persistence, as well as database management. 

Q30) Can nodes be added easily in the Couchbase or there are some special conditions which need to be fulfilled?

It is possible to add nodes without meeting the complex criteria in Couhbase.

Q31) How will you define Couchbase Server?

Couchbase Server is a fast, seamless, NoSQL database which was initially termed as Membase. It is a software package which is technologically advanced multi-model NoSQL, and is file-oriented. It has been proposed for interacting through web applications.

Q32) Is Couchbase amultiform NoSQL file oriented database software package?

The answer to this question is yes, Couchbase is a distributed multiform NoSQL file-oriented database software package. Couchbase is generally defined as open source software which was released under Apache license that consisted of a community and enterprise edition.

Q33) Why is Couchbase more advanced than MongoDB?

MongoDB provides multi-step scalability, whereas, Couchbase offers a seamless scalability property. The reason why Couchbase is more advanced than MongoDB is due to the consistency. Couchbase arrives with a high consistency power; while on the contrary, MongoDB offers a low consistency power. Plus, Couchbase’s uptime is always up. While on the other hand, MongoDB’s uptime needs a bit of maintenance.

Q34) Generalize the features of the Couchbase server.

1. Couchbase server has gained massive importance currently. The reasons why it is highly used by operators have been mentioned below. [Note: the points are the features of the Couchbase server.]
2. Couchbase is fast. Known for the quickness, the Couchbase server provides highest sustained throughput with lower latency. What remarkable is, the performance cost is affordable and inexpensive.
3. In addition, Couchbase server features an easy and simple UI. One can install, manage, and expand the usage. The server doesn't require the necessity of maintaining or creating schemas. It also doesn’t require normalizing or even tuning the database.
4. Couchbase server ensures to distribute data as well as commodity servers or the virtual machines. This is what makes it easy to relate the quantity of resources optimally. It also ensures to the varying needs of the application. The nodes within the server enhance which ranges from 1-100 tons (in a cluster).
5. Finally, Couchbase is not only stable but also enterprise-based software that can be relied on.

Q35) What is the difference between Couchbase and CouchDB?

Couchbase is capable enough of storing key-values as well as credentials. Thus, it can store data like binary data, JSON documents, and many more.Couchbase server makes use of a binary Memcached protocol to perform the high-end functionalities as well as REST API’s SQL in order to view the queries.

Apache CouchDB, on the contrary, is capable of storing JSON documents. It also provides facilities to attach non-JSON files to the JSON documents.

Q36) What are the important advantages of including Couchbase and CouchDB into a single product?

First and foremost, Couchbase server happens to be a super-fast and highly scalable key-value store which is known for its high-end scalability as well as performance. Secondly, CouchDB, on the contrary, is an excellent document database that comes with powerful querying as well as indexing capabilities. So combining the aforementioned two would be beneficial. Not only will it create a high-end performance, but also highly elastic NoSQL database that will scale out the linearly. At the same time, it will also provide indexing, querying as well as other document-oriented features. Hence including Couchbase and CouchDB will be beneficial.

Q37) Briefly explain the four subsystems that function on each node

The four subsystems that function on each node are Pulses, Progression Monitor, Worldwide Singleton Supervisor, and Pattern Manager. The explanations have been mentioned right below.

1. Pulses – A set of words are exchanged by the Watchdog developers regularly. The exchanging process is carried forward with the currently chosen cluster head in order to provide well being revises.
2. Worldwide Singleton Supervisor – Worldwide Singleton Supervisor, is one of the subsystems which is tasked to select the cluster heads only in case the previously voted head stops.
3. Progression Monitor – Progression Monitor is that subsystem which helps in monitoring in carrying out the limited executive. Thereby, it resumes unsuccessful procedure as per the need. Finally, it contributes state data to those beating piece.
4. The Pattern Manager – Each node in the set features a specific pattern, for example,the intention map or vBucket map, so on and so forth. Pattern Manager receives, monitors and process the local configuration.

Q38) Briefly explain the two TCP ports used to listen to requests

The port numbers which have been configured are Port 11210 and Port 11211. The explanations have been mentioned right below.

  • Firstly, Port 11210 happens to be a port that is openly accessible to the clients implementing a version of 2.0 of memcapable API. These are the ‘vBucket aware’ client. They are depending and hashing algorithm to the map keys to an appropriate ‘vBuckets’ number. Later on, the vBuckets are mapped to the respective server and thereby provides a coating of indirection that enables the rebalancing of the vibrant cluster. Also, it offers replication, failover, as well as group expansion or contraction.
  • Secondly, Port 11211 happens to be the Memcached port number which processes the request from the clients guiding 1.0 version of API requirement. These clients depend on the consistent algorithm to the map keys in order to serve a catalog for length server.

Q39) What do you mean by Data Manager and Cluster Manager in Couchbase Server?

Couchbase server involves two functional blocks (Data Manager and Cluster Manager), which are explained right below.

1. Data Manager – It is responsible for extracting and storing the data from apps. Data Manager discloses two ‘memcapable’ docks within the sets of connections. The non-vBucket aware client libraries are guided by 1 port. On the contrary, the vBucket aware client libraries will be guided by another one. Almost all data manager code has been written in the C and C++ programming languages.

2. Cluster Manager – It is designed in order to look after the performance as well as the arrangement of the nodes in the couchbase server cluster. The Manager's code will be running on every lump in clusters. After that, it chooses on the node for the purpose of aggregation. Almost all Cluster Manager Code has been written in Erlang/OTP.

Q40) Can Couchbase speed up the accession to any database document by catching it in memory automatically?

The answer is, definitely,Couchbase has the capability of speeding up access to any database document by automatically catching it in the memory.

Q41) How does Couchbase speed up the accession to a particular database document automatically via memory?

Couchbase Server 2.0 comes from a host of experiences with memcached. The accession to the documents is gone through the integrated RAM caching layer that has been made up of memcached. This helps in providing low and predictable latency under immensely heavy loads.

Q42) What do you mean by Storage Engine in Couchbase?

Couchbase Server features a design philosophy of a tail-append storage. It is immune to data corruption, sudden power loss, or even OOM killers. Data happens to be written in the data file that enables Couchbase to mostly do sequential write-ups for an update. Also, it provides an optimized and enhanced access patterns for disk I/O.

Q43) What Is Document in Couchbase?

In Couchbase, a document usually refers to an entry in the database. A document consists of an ID that happens to be unique by nature. Its value contains the real application data. Documents are stored on the server as JSON. While JSON is a structured format happens to be a structured format, it can be searched and accordingly get queried by following the below-mentioned command.

{
“type”: “product”,
“sku”: “CBSRV45DP”,
“msrp”: [5.49, “USD”],
“ctime”: “092011”,
“mfg”: “couchbase”,
“tags”: [“server”, “database”, “couchbase”, “nosql”, “fast”, “json”, “awesome”]
}

Q44) What Is N1QL?

N1QL happens to be a query language or the non-first usual form of the query language. It is purposed to manipulate JSON data in the Couchbase server. Some of its statements to operate the JSON data are as follows:

1. INSERT
2. DELETE
3. UPDATE
4. MERGE
5. SELECT

Q45) What do you mean by Object-managed Cache in the Couchbase Server?

Couchbase Server comprises an object-managed, built-in, and multi-threaded cache. The cache is capable of implementing APIs that are memcached compatible, for example, append, prepend, set, get, and more.

Q46) Explain the role of Data Structures in the Couchbase server.

In Couchbase, Data structures are similar to that included inJavaScript.Map is a key-value structure that is similar to a JavaScript Object. In Map, a value is accessed by employing the key string. One can place the values in the very beginning or at the end.

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