50+ Best Couchbase Interview Questions

Last updated on 09th Nov 2021, Blog, Interview Questions

Couchbase Server presents high availability for reading and writing of data through a type of feature. Couchbase implements high availability utilizing intra-cluster replication and index replication, and disaster recovery working cross datacenter replication (XDCR). These Couchbase Interview Questions have been formed mainly to get you begun to the nature of questions you may mark completely your interview for the subject of Couchbase. As per my expertise, big interviewers unusually plan to ask a suitable question while your interview, constantly questions start with some primary concept of the subject, and later they progress based on further analysis and what you respond to. We are progressing to include the best 100 Couchbase Interview questions concurrently with their comprehensive answers. We will be incorporating Couchbase scenario-based interview questions, Couchbase interview questions for freshers as well as Couchbase interview questions and answers for sophisticated.

1. Compare Couchbase and MongoDB?

Ans:

Criteria	Couchbase	MongoDB
Scalability	Seamless scalability	Multi-step scalability
Consistency	High	Low
Uptime	Always up	Needs maintenance

2. Is Couchbase an open source software?

Ans:

Yes. Couchbase can be recognized as an open source software released under the Apache 2.0 license with an enterprise and community edition. Couchbase is a distributed multiform NoSQL file oriented database software package that is advanced for collective applications and open-source software.

3. What is Couchbase Server?

Ans:

Couchbase server is an easy, fast, elastic NoSQL database. It is also known as Membase, distributed, multi-model NoSQL file oriented database software package that is advanced for collective applications.

4. What are the basic features of the Couchbase server?

Ans:

Fast – Couchbase is known for its quickness. Couchbase server facilitates the lower latency and highest throughput. The performance cost will be low and it is a remarkable sign .

Simple – Couchbase server is simple in terms of managing, installing, getting, expanding and using it. In a Couchbase server, it is not necessary to create and manage schemas, as a document database without normalizing and tuning of the database.

Elastic – The Couchbase server will distribute the data and I/O over virtual machines or commodity servers, thus it can make it easy to relate the optimal quantity of resources to the changing needs of an application. In couchbase server the nodes can be enhanced from 1 to 100 tons in a cluster and also can get reduced to sustain application performance.

Reliable – Couchbase server is stable and enterprise-ready software, so anyone can rely on mission critical applications.

5. What is vBucket?

Ans:

Vbucket is one of the ways of logically partitioning data because of this nature, it can distribute all over the nodes in a cluster. Each couchbase kind bucket that gets created in the cluster is automatically split up into a static set of slices, later they map to individual servers. They are used to allocate the information effectively along with throughout a cluster.

6. What are the 4 subsystems which function on every node?

Ans:

Pulses : Watchdog develops regularly exchange a few words with the presently designated cluster head to offer wellbeing revises.

Progression Monitor : This is the subsystem to monitor on carrying out of the limited information executive, resuming unsuccessful procedures as needed and contributing condition data to the pulsing piece.

Pattern Manager : It is known that every node in the cluster has a pattern example: vBucket map, an intention map, etc. This subsystem will receive, monitor and process local configuration.

Worldwide Singleton Supervisor : This is of the subsystems and its task is to select cluster head if the previously voted head dies and monitoring “per-cluster” carries if the neighboring lump is the present chief.

7.What vBucket Map represents?

Ans:

The vBucket map is responsible for representing the state of a cluster once a currently running rebalance operation completes. The process called Rebalance Orchestrator correlate the target current maps to conclude which movement Tap Streams to create and administer. The operation of Rebalance will get exhaustive when the current and Target vBucket Maps are alike.

8. What are the TCP ports used to listen to the requests?

Ans:

The port numbers are configurable. The default ports are as below:

Port 11210 : It is a port which is openly accessible to clients implementing version 2.0 of the memcapable API. Those are “vBucket aware” clients and are depending on the hashing algorithm to map keys to one of a suitable number of “vBuckets”. The vBuckets later will get mapped to a server, providing a layer of indirection enabling vibrant cluster rebalancing, non-disruptive cluster expansion or contraction, replication and failover.

Port 11211 : The usual Memcached port number processes requests from, clients guiding version 1.0 of the memcapable API requirement. Those clients will be depending on a consistent hashing algorithm to map keys openly to servers in a variable-length server catalog.

9. What is the importance of creating a Data Bucket?

Ans:

It makes important to create a Data Bucket since the couchbase server stores the data in Data Buckets. The “Default” bucket is created when the couchbase server is installed. The capacity of a data bucket to store the data is up to 20MB. If required, additional data buckets can be added. The bucket creation will have a limit when there is no sufficient space in RAM. Ex: limit the RAM/ Quota usage for the default bucket to 100 MB.

10. Compare Kafka and Flume?

Ans:

Criteria	Kafka	Flume
Data flow	Pull	Push
Hadoop integration	Loose	Tight
Functionality	A Publish–Subscribe model messaging system	A system for data collection, aggregation, and movement

11. What are the elements of Kafka?

Ans:

The most important elements of Kafka are as follows:

Topic: It is a bunch of similar kinds of messages.

Producer: Using this, one can issue communications to the topic.

Consumer: It endures to a variety of topics and takes data from brokers.

Broker: This is the place where the issued messages are stored.

12. What role does ZooKeeper play in a cluster of Kafka?

Ans:

Apache ZooKeeper acts as a distributed, open-source configuration and synchronization service, along with being a naming registry for distributed applications. It keeps track of the status of the Kafka cluster nodes, as well as of Kafka topics, partitions, etc.

Since the data is divided across collections of nodes within ZooKeeper, it exhibits high availability and consistency. When a node fails, ZooKeeper performs an instant failover migration.

ZooKeeper is used in Kafka for managing service discovery for Kafka brokers, which form the cluster. ZooKeeper communicates with Kafka when a new broker joins, when a broker dies, when a topic gets removed, or when a topic is added so that each node in the cluster knows about these changes. Thus, it provides an in-sync view of the Kafka cluster configuration.

13. What is Kafka?

Ans:

Kafka is a message divider project coded in Scala. Kafka was originally developed by LinkedIn as an open-source project in early 2011. The purpose of the project was to achieve the best stand for conducting the real-time statistics nourishment.

14. Why do you think the replications to be dangerous in Kafka?

Ans:

Duplication assures that the issued messages available are absorbed in the case of any appliance mistake, plan fault, or recurrent software promotions.

15. What major role does a Kafka Producer API play?

Ans:

It is responsible for covering two producers: kafka.producer.SyncProducer and kafka.producer.async.AsyncProducer. Kafka Producer API mainly provides all producer performance to its clients through a single API.

16. Describe partitioning key?

Ans:

Its role is to specify the target divider of the memo within the producer. Usually, a hash-oriented divider concludes the divider ID according to the given factors. Consumers also use tailored partitions.

17. Inside the manufacturer, when does the QueueFullException emerge?

Ans:

QueueFullException naturally happens when the manufacturer tries to propel communications at a speed which a broker can’t grip. Consumers need to insert sufficient brokers to collectively grip the amplified load since the producer doesn’t block.

18. Can Kafka be utilized without ZooKeeper?

Ans:

It is impossible to use Kafka without ZooKeeper because it is not feasible to go around ZooKeeper and attach it in a straight line with the server. If ZooKeeper is down for a number of causes, then we will not be able to serve customers’ demands.

19. Elaborate the architecture of Kafka.

Ans:

In Kafka, a cluster contains multiple brokers since it is a distributed system. Topic in the system will get divided into multiple partitions, and each broker stores one or more of those partitions so that multiple producers and consumers can publish and retrieve messages at the same time.

20. How to start a Kafka server?

Ans:

Given that Kafka exercises ZooKeeper, we can start the ZooKeeper’s server. One can use the convince script packaged with Kafka to get a crude but effective single-node ZooKeeper instance:

bin/zookeeper-server-start.shconfig/zookeeper.properties

Now the Kafka server can start:

bin/Kafka-server-start.shconfig/server.properties

21. Describe an Offset?

Ans:

The messages in partitions will be given a sequential ID known as an offset, and the offset will be used to identify each message in the partition uniquely. With the aid of ZooKeeper, Kafka stores the offsets of messages used for a specific topic and partition by a consumer group.

22. What do you know about a partition key?

Ans:

A partition key is used to point to the aimed division of communication in Kafka producer. Usually, a hash-oriented divider concludes the division ID with the input, and also people use modified divisions.

23. How can you say that a Couchbase Server is different from that of database software?

Ans:

Criteria	NoSQL	RDBMS
Data format	Does not follow any order	Organized and structured
Scalability	Very Good	Average
Querying	Limited as no Join Clause	Using SQL
Storage mechanism	Key-Value Pair, document, column storage, etc.	Data & relationship stored in different tables

24. What does N1Ql stand for?

Ans:

It stands for the non-first normal form query language

25. What do you know about a shared server and a dedicated server?

Ans:

Organizations and businesses these days have the option to consider a server that 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 a 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.

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

Ans:

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.

27. What are the functional blocks involved in Couchbase Server?

Ans:

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

• Data Manager
• Cluster Manager

28. What is a data manager in the Couchbase Server?

Ans:

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 certainly other important tasks which it performs and without making an impact on the overall functionality of the software

29. Tell something about the Data Format in the Couchbase server?

Ans:

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.

30. Tell something about the features of Couchbase you are familiar with?

Ans:

There are certain features that make it simply the best. Couchbase is fast and known to process 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 critical applications.

31. What Is Document in Couchbase?

Ans:

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 that 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”]
• }

32. What Is N1QL?

Ans:

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:

• INSERT
• DELETE
• UPDATE
• MERGE
• SELECT

33. What do you mean by Object-managed Cache in the Couchbase Server?

Ans:

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.

34. Explain the role of Data Structures in the Couchbase server?

Ans:

In Couchbase, Data structures are similar to those included in javascript.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.

35. What is Couchbase as Document Store

Ans:

The primary unit of data storage in Couchbase Server is a JSON document, which makes your application free ofrigidly-defined relational database tables. Because application objects are modeled as documents, schema migrations do not need to be performed. The binary data can be stored in documents as well, but using JSON structure allows the data to be indexed and queried using views. Couchbase Server provides a JavaScript-based query engine to find records based on field values.

36. What is Data Buckets

Ans:

By using a juggling-check, we can check both null and undefined:

The data is stored in a Couchbase cluster using buckets. Buckets are isolated, virtual containers which logically group records within a cluster. A bucket is the equivalent of a database. They provide a secure mechanism for organizing, managing and analyzing data storage.

37. What is Couchbase SDK?

Ans:

Couchbase SDKs (aka client libraries) are the language-specific SDKs provided by Couchbase. A Couchbase SDK is responsible for communicating with the Couchbase Server and provides language-specific interfaces required to perform database operations.

All Couchbase SDKs automatically read and write data to the right node in a cluster. If database topology changes, the SDK responds automatically and correctly distributes read/write requests to the right cluster nodes. Similarly, if your cluster experiences server failure, SDKs will automatically direct requests to still-functioning nodes.

38. Define the Architectural Overview of Couchbase?

Ans:

Note that this scheme relies on thick clients embodied in the API libraries that applications use to communicate with Couchbase. Thick clients are in constant communication with server nodes. They fetch the updated cluster map, then reroute requests in response to the changed topology. In addition, they participate in load-balancing requests to the database. The work done to provide load balancing is actually distributed among the clients.

39. What is Querying data in Couchbase?

Ans:

There are two patterns for querying data from Couchbase. The most efficient one is via key pattern. If the key of the document is known, the complexity of retrieval of the documents is O(1). It is also possible to retrieve multiple documents using multi-get. Using batch retrieval is very efficient when the client need to deal with a list of documents, because the number of client round-trip calls is reduced.

40. How was the Performance measured in Couchbase?

Ans:

Performance should be measured for meaningful workloads. This can help to understand performance characteristics for certain situations and choose the right NoSQL technology.

One of the benchmarks conducted to compare NoSQL technologies is called: YCSB (Yahoo Cloud Serving Benchmark). Its purpose is to focus on databases and on performance. It is open-source, extensible, has rich selection of connectors for various database technologies, it is reproducible and compares latency vs throughput.

41. How Performance and consistency executed in read/write operations in Couchbase?

Ans:

To ensure consistency, it is important to execute the read/write operations on the primary nodes only. The NoSQL solutions which have only one primary node are limited from the performance point of view, because clients cannot leverage secondary nodes. The first alternative is to execute read operations on all nodes (primary and secondary). In that case, read performance is better, but no longer consistent because replication is asynchronous by default. The second alternative is synchronous replication. Which leads to consistent data, but performance degradation.





All the read/write operations are performed on the primary nodes.

42. How Couchbase Monitoring the statistical analysis?

Ans:

Couchbase Server incorporates a complete set of statistical and monitoring information. The statistics are provided through all of the administration interfaces. Within the Web Administration Console, a complete suite of statistics are provided, including built-in real-time graphing and performance data.



The statistics are divided into a number of groups, allowing you to identify different states and performance information within your cluster:

By Node – Node statistics show CPU, RAM and I/O numbers on each of the servers and across your cluster as a whole.

By vBucket – The vBucket statistics show the usage and performance numbers for the vBuckets used to store information in the cluster.

By View – View statistics display information about individual views, including the CPU usage and disk space used so that you can monitor the effects and loading of a view on Couchbase nodes.

By Disk Queues – monitor the queues used to read and write information to disk and between replicas. Can be helpful in determining whether the cluster should expand to reduce disk load.

43. How can we find and fix a Rails and Couchbase memory leak?

Ans:

We can add API in Couchbase by using the code below:

• def loop_bucket_gets
• bucket = Couchbase::Bucket.new({:node_list => [‘xxx.xxx.xxx.xxx:8091’, ‘yyy.yyy.yyy.yyy:8091’],
• :bucket => ‘Foo’,
• :pool => ‘default’/li>,
• :expires_in => 1.day,
• :default_format => :marshal,
• :key_prefix => ‘_foo’
• })
• i = 0
• loop do
• begin
• i += 1
• bucket.get “ABC#{i}”
• rescue ::Couchbase::Error::Base => e
• nil
• end
• end
• end

44. How can we use HTTPS replication with iOS Couchbase Mobile?

Ans:

45. How to merge data in Couchbase with map reduce?

Ans:

We can merge data by using the code given below:

• function(doc, meta) {
• var getStep = function(stepName, exit, mapper)
{
• if (meta.id.indexOf(stepName) !== -1) {
• var hotelId = parseInt(meta.id.replace(stepName + ‘_’, ”));
• if (hotelId > 0) {
• var result = {
• hotelId: hotelId,
• exit: exit
• };
• if (mapper !== undefined) {
• mapper(result);
• }
• return result;
• }
• }
• return null;
• };
• var photos = getStep(‘PHOTOS’, 7);
• if (photos != null) {
• emit(photos.hotelId, photos);
• }
• var pricing = getStep(‘PICR’, 5);
• if (pricing != null) {
emit(pricing.hotelId, pricing);
• }
• var owner = getStep(‘OWNER’, 1);
• if (owner != null) {
• emit(owner.hotelId, owner);
• }
• var amenity = getStep(‘AM’, 4);
• if (amenity != null) {
• emit(amenity.hotelId, amenity);
• }
• var description = getStep(‘HDESC’, 3, function(result)
{
• result.description = doc.description;
• result.hotelRoomTypeId = doc.hotelRoomTypeId;
• result.starRating = doc.starRating;
• });
• if (description != null) {
• emit(description.hotelId, description);
• }
• var contact = getStep(‘DC’, 3, function(result) {
• result.email = doc.emailAddress;
• result.contact = doc.mainContactName;
• });
• if (contact != null) {
• emit(contact.hotelId, contact);
• }
• var location = getStep(‘LOC’, 2, function(result) {
• result.city = doc.cityName;
• result.zip = doc.postalCode;
• result.country = doc.countryName;
• result.street = doc.stateName + ‘, ‘ + doc.streetName;
• });
• if (location != null) {
• emit(location.hotelId, location);
• }
• var property = getStep(‘PRP’, 1, function(result) {
• result.paymentMethodId = doc.paymentMethodId
• });
• if (property != null) {
• emit(property.hotelId, property);
• }
• }

46. What is a Bucket in Couchbase?

Ans:

Couchbase Buckets are in storing data which can be flushed, created, deleted and edited, and also helps in storing the items in the buckets. It supports indexing, replication, data persisting, N1Ql queries, views and caching.

Bucket types in Couchbase are as follows:

• Couchbase Buckets

• Memcached Buckets

• Ephemeral Buckets

47. Is CouchDB used in the Software industry?

Ans:

CouchDB is very popular now a day, and many companies are using CouchDB.

These are the essential features of CouchDB:

• CouchDB can be replicated across multiple server instances.
• CouchDB has various libraries for the language of your choice.
• It has fast indexing and retrieval
• It has a REST-like interface for document insertion, updates, recovery, and deletion.
• CouchDB supports JSON-based document format, i.e., easily translatable across different languages.

That’s why the software companies use CouchDB.

Here we have a list of Top companies which uses CouchDB:

Company	Website	Revenue	Company size	Country
GrubHub Inc.	grubhub.com	200M-1000M	1000-5000	United States
Hothead Games, Inc.	hotheadgames.com	10M-15M	50-200	Canada
Ultimate software group 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

48. Why Does CouchDB not use Mnesia?

Ans:

There are many reasons behind CouchDB not using Mnesia:

• It provides a storage limitation of 2 gigs per file.
• It requires validation and fixup cycle after a crash or power failure, so even if the size limitation is lifted, the fixup time on large files is prohibitive.
• Mnesia has some useful features, but features of Mnesia aren’t really useful for CouchDB.
• Mnesia is not a general-purpose, large-scale database. It works best as a configuration type database.
• Mnesia works best as a configuration type database. It is necessary for the normal operations. The type where the data is not central to the function of the application, but necessary for normal operation of it.
• Things that need to update, configure and often reconfigure like a network router, HTTP proxies, etc. whose configuration data is rarely huge.

49. How would you use transactions with CouchDB?

Ans:

CouchDB uses an “Optimistic concurrency” model. In this model, if you send a document version along with your update, CouchDB rejects the change if the current document version doesn’t match to your sent update.

So, you have to re-frame many normal transaction based scenarios for CouchDB. It’s helpful to approach problems from a higher level, rather than attempting to mold Couch to a SQL based world.

If you have a document describing the item, and it includes a field for “Quantity available”, you can handle concurrency issues

First of all recover document, note down property that sent by CouchDB along with database, after that, Decrement the quantity field, if it’s greater than zero. After that, send the updated document back using the _rev property. Check, If the _rev matches the currently stored number, be done else if there is a conflict when _rev is not matched then recover the newest document version.

Example

I would like to take a (“master product”) document that contains all the data information like name, picture description, price, etc. Here we have to create to a field (product-key and, Claimed-by) by adding a new document inventory-ticket, if you are spelling a model of a hammer and have 20 items to sell, you might have documents with keys like hammer-1, hammer-2 to represent each one individually.

• Map
• Function (doc)
• {
• If(doc.type== ‘inventory-ticket’ && doc.claimed_by==null)
• {
• emit(doc.product_key, { ‘inventory-ticket’ :doc.id, ‘_rev’ : doc._rev});
• }
• }
• Reduce
• Function (keys, values, combine)
• {
• Return values.length();
• }
This example represents that transaction with CouchDB is possible that it substantially reduces conflicting updates, and cut down on the needs to respond to a conflict with the new updates. In this model, you won’t have multiple users attempting to change data in primary product entry. When you have multiple users for a single ticket, then you have to identify those users who want to retake it by your view, ignore those, and you move to the next ticket and try again.

50. As CouchDB is written in Erlang and Erlang is known as slow to adopt Unicode. So, if it creates a problem for CouchDB?

Ans:

CouchDB uses Erlang binary internally. So, data come to CouchDB is always UTF-8 encoded. There is no problem occurred.

51. What do you know about couchdbKit?

Ans:

The couchdbKit provides a framework for your Python application to access and manage Python applications. It offers features to easily access and manage CouchDB by a client, allow to manage databases, Couch database server, doc management, and view access.

Objects mostly reflect python object for service. Server and data objects could be used for example.

Steps to install couchdbkit:

• Couchdbkit requires python 2.x superior to 2.6
• To install Couchdbkit using pip you must make sure that you have a recent version on distribute installed.
• $ curl -0 http://python-distribute.org/distribute_setup.py
• $ curl sudo python distribute_setup.py
• $ easy_install pip

To install or upgrade to a latest released version of couchdbkit

$ pip install couchdbkit

52. How can you do replication?

Ans:

Replication: Replication synchronizes two copies of the same database; these databases live on the same server or can be live on two different servers. If you change one copy of the database, replication will send the details to another copy.

For replication, first you have to send request of HTTP to CouchDB with a source, and a target database and CouchDB will send the changes from source to target.

Let’s see, how replication looks like:

• POST /_replicate with a post body of
• {“source”:”$source_database”
• ,
• “target”:”$target_database”}

Here $source_database and $target_database can be the names of local database or full URIs of remote databases. Both databases need to be created before they can be replicated from or to.

53. What is Index in Couchbase?

Ans:

Multiple TCP ports are used by Couchbase Server to facilitate the network communication between Couchbase clients, as well as with server components. Some various ports are used for cluster management. The TCP ports enable the Couchbase server to work correctly. The other ports are used by the Couchbase services and only opens on the required nodes where services are running.

54. What is the Couchbase Cluster?

Ans:

Couchbase Cluster mainly contains one or more instances of Couchbase Server running on an independent node. In Couchbase, the new cluster is created by setting a cluster with an initial node of the Couchbase Server. Couchbase Cluster replicates data over Server instances to ensure high availability.

55.What is the full-text search in Couchbase?

Ans:

Full-text Search in Couchbase will allow you to query, create, and manage specially purposed indexes defined on the JSON document present within a Couchbase bucket. It provides Google-like search capabilities on JSON documents. Extensive capabilities are provided by Full-text Search (FTS) for natural language querying. Full-text search is powered by open-source indexing and search library called Bleve.

56. What is the use of Cluster Manager in Couchbase?

Ans:

Basically, Cluster Manager in Couchbase runs on all the nodes of a cluster. The Cluster Manager coordinates cluster-wide operations and maintains essential pre-node processes. The architecture of the cluster manager mainly consists of two processes such as babysitter and ns-server. The babysitter is responsible for maintaining a wide variety of Couchbase Server Processes. Ns-server is mainly used to manage the node’s participation in the cluster.

57. What is a Couchbase Server Node?

Ans:

Basically, the Couchbase Server contains one or more nodes, and each of which is a system running a single Couchbase Server instance. The node is a virtual or physical machine and its main aim is to host a single instance of Couchbase Server. The Couchbase Server is established on a node in four stages such as 1. Installed 2. Started 3. Initialized 4. Provisioned. The node can be a cluster of one server only when a variant of the fourth stage is achieved. You can add a node to the cluster after installation or during the installation.

58. What are Data Structures in Couchbase?

Ans:

Data structures in Couchbase are similar in concept to data structures in JavaScript:

Map is like a JavaScript Object and is a key-value structure, where a value is accessed by using a key string.

List is like a JavaScript array and is a sequential data structure. Values can be placed in the beginning or end of a list and can be accessed using numeric indexes.

Set is a wrapper over a list which provides the ability to handle unique values.

59. What are the different parts in the Basic N1ql Query?

Ans:

A basic N1QL query has the following parts:

SELECT — The fields of each document to return.

FROM — The data bucket in which to look.

WHERE — The conditions that the document must satisfy.

60.What are the capabilities of a core database engine?

Ans:

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.

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

Ans:

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.

62. What is Query Workbench?

Ans:

The Couchbase Web Console provides a Query Workbench, at which you can compose and execute N1QL queries.

63. What’s it like to work for Couchbase?

Ans:

Well, I’ve built and led developer communities for 10+ years at Sun, Oracle, and Red Hat, so I have experience in leading crossfunctional teams to develop and execute strategy, planning, and execution of content, and marketing campaigns and programs. I’ve also led engineering teams at Sun, and I’m a founding member of the Java EE team.

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

Ans:

Basic knowledge about the network and 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 depending on the task assigned to you.

65. Name the language in which CouchDB can be written?

Ans:

CouchDB is written in Erlang which is a concurrent, functional programming language that focuses on fault tolerance. This is used for building massively scalable soft real-time systems with requirements of high availability. However, some of its parts are written in C language too.

66. Which language was first used in CouchDB?

Ans:

CouchDB’s work was started in C++ language. But later, it was replaced by the Erlang OTP platform.

67. Differentiate between CouchDB and SQL databases?

Ans:

In CouchDB, JSON-based document formats are used for storing data, JavaScript for MapReduce indexes, and regular HTTP of its API. This includes the Couch database that is used for storing data in the JSON document. In this, you query your index and documents with the help of a web browser via HTTP. This is implemented in the Erlang programming language While SQL database uses RDBMS for storing data. It is a very fast, Multi-user, Multi-thread, and robust SQL (structured query language) database server. This is also used for big data storage of a large project. Further, it is a NoSQL database with manual transmission. This is implemented in C, C++ programming languages.

68. Given an open source technology what are the other good things that you know about the Cloudbase?

Ans:

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

69. Name the major elements that CouchDB offers?

Ans:

The components include: JSON Documents RESTful Interface N-Master Replication Built for Offline Replication Filters ACID semantics Document storage Authentication and Session Support Security Map/Reduce List and Show

70. Differentiate between PouchDB and CouchDB?

Ans:

PouchDB is also a CouchDB client, in which you can switch between a local database or an online CouchDB instance without changing any of your application’s code. However, CouchDB uses ICU for ordering keys in a view query, and in PouchDB they are ASCII ordered. Further, CouchDB returns an offset property in the view results. Whereas, in PouchDB, offset just mirrors the skip parameter instead of returning a true offset.

71. Define the strict upper limit on the storage capacity of a data bucket in Couchbase Server?

Ans:

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

72. Can you define IBM’s Involvement in CouchDB?

Ans:

The main outcomes of IBM’s involvement are: Firstly, the code is now being Apache-licensed, instead of GPL. Secondly, Damien is going to be contributing more time.

73. What is data replication?

Ans:

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

74. How will you improve CouchDB performance?

Ans:

• Firstly, we can try using the built-in Erlang functions like _sum , _count , instead of writing Javascript. Since complex views can take alot of time.
• Also, try to post such not too complex map/reduce.
• Lastly, do not forget: indexing all docs is only done once after changing the view (or pushing a whole bunch of new docs)

75. As a developer advocate, how do you encourage developers to participate and contribute to open source NoSQL database projects?

Ans:

Open source NoSQL database projects, and the community in general, benefit enormously from developer participation and contributions. Whether on their own time, or as part of their everyday job, developers are the people who make these products happen. When I talk with enthusiastic developers who want to be a part of this great adventure, I usually suggest:

• GitHub is the center of the universe. If you’re not familiar with it already, you need to be.
• Pick a project that you like, or better yet one that you use, and become an expert in that project. Get corporate backing by asking your company to dedicate some or all of your time towards contributing back to the open source projects that they use.
• Find an area of the project that you are passionate about, and start your contributions there. You know, it’s not always about writing new features – there are APIs to develop, storage options to consider, integration with other tools and projects, as well as examples, documentation, and test suites that need continuing review and improvement. Focusing on documentation, for example, can be of tremendous value to you and to many others in the community.
• Solve real world problems. The contributions that make the biggest impact to the community are the ones that solve a problem that many people encounter.
• It can be a problem in any of the areas above. Odds are, if it’s a problem for you, then it’s a problem for other users as well.
• Most open source projects have processes to encourage participation and contributions—find them and use them. Couchbase, for example, dedicates an entire section of our developer portal to working with the community. It includes a list of the available open source projects, access to the developer forums, how to engage with the Experts and Champions program, as well as a monthly developer newsletter.​

76. What is the Query Service in Couchbase?

Ans:

The Couchbase Query Service supports the querying of data by means of the N1QL query language.



Its architecture and the query processing-sequence it supports are explained in Query Service.

77. What is the multidimensional scaling architecture in Couchbase?

Ans:

Couchbase Server supports multidimensional scaling, whereby services can be distributed and resourced with the greatest flexibility, across the designated nodes of a cluster.

78. What is the Data-Service Rebalance Stages in Couchbase?

Ans:

Rebalance redistributes data, indexes, event processing and query processing among available nodes. Data is moved in stages, the progress through which is observable, allowing rates of progress to be determined.

79. How Durability used in Couchbase?

Ans:

Couchbase Server provides durability, which ensures the greatest likelihood of data-writes surviving unexpected anomalies, such as node-outages.

80. Which are the Search Service in Coucbase?

Ans:

 TypeScript supports following data types.

81. How Cluster Manager runs in Couchbase server?

Ans:

The Couchbase Cluster Manager runs on all the nodes of a cluster, maintaining essential per-node processes, and coordinating cluster-wide operations.

82. How Couchbase implemented a Data Size Limits?

Ans:

A data-item stored by Couchbase Server has multiple inner components, each of which has a fixed size limit.

83. How Compression is used in Couchbase server?

Ans:

Compression is used by Couchbase Server to maximize resources and heighten performance.

84. How can Memory Quotas implemented for Couchbase?

Ans:

Couchbase Server monitors the memory used by buckets with respect to fixed memory quotas. If watermarks are exceeded, automated management action is taken, to ensure that the data items most needed are retained in memory, and those less needed removed.

85. How Can Couchbase Be Integrated With Big Data And Sql?

Ans:

Couchbase Data Platform includes integrated Big Data and SQL integration, allowing you to leverage equipment, processing ability, and records wherever it is able to are living.

86. How Container And Cloud Deployments In Couchbase?

Ans:

Couchbase helps all cloud platforms, in addition to an expansion of box and virtualization technology to enable operational excellence.

87. Can You Explain About Role-primarily based Access Control Authentication?

Ans:

Role-Based Access Control. This ensures that cluster-resources can simplest be accessed with the aid of users with appropriate privileges. Privileges are grouped in Couchbase-described units; and each set is associated with a selected function. Users can every be assigned one or more roles, and are hereby granted the privileges associated with each role.

88. What Is Document in Couchbase?

Ans:

A record refers to an entry inside the database (different databases might also consult with the identical concept as a row). A record has an ID (number one key in other databases), which is specific to the file and with the aid of which it can be placed.

The file fee incorporates the actual application statistics; for instance, a product file may additionally comprise records approximately the fee and outline. Documents are commonly ( however no longer always) saved as JSON on the server. Because JSON is a structured layout, it is able to be sooner or later searched and queried.

89. What Is Cross Datacenter Replication (xdcr)?

Ans:

XDCR involves replicating active information to N+1 Couchbase Server clusters or external packages (e.G. Elastic, Spark, Storm, and many others.). The clusters are often used for multiple, geographically numerous datacenters either for disaster recuperation or to carry information in the direction of users for faster statistics get admission to. For Couchbase clusters, this replication can be installation to be bi-directional or multi-directional.

90. What Is Object-managed Cache In Couchbase Server?

Ans:

Couchbase Server includes a integrated multi-threaded item-controlled cache that implements memcached well matched APIs along with get, set, delete, append, prepend and so on.

91. What Is Storage Engine In Couchbase Server?

Ans:

Couchbase Server has a tail-append storage layout that is resistant to data corruption, OOM killers or unexpected loss of strength. Data is written to the statistics record in an append-handiest way, which allows Couchbase to do mostly sequential writes for replace, and provide an optimized get right of entry to styles for disk I/O.

92. What Is Analytics In Couchbase?

Ans:

Couchbase Analytics presents powerful parallel query processing. Designed to correctly execute complicated, lengthy-walking queries that comprise complicated joins, set, aggregation, and grouping operations.

93. Why Does CouchDB Not Use Mnesia?

Ans:

Several reasons:

• The first is a storage limitation of 2 gig per file.
• The second is that it requires a validation and fixup cycle after a crash or power failure, so even if the size limitation is lifted, the fixup time on large files is prohibitive.
• Mnesia replication is suitable for clustering, but not disconnected, distributed edits. Most of the “cool” features of Mnesia aren’t really useful for CouchDB.
• Also Mnesia isn’t really a general-purpose, large scale database. It works best as a configuration type database, the type where the data isn’t central to the function of the application, but is necessary for the normal operation of it. Think things like network routers, HTTP proxies and LDAP directories, things that need to be updated, configured and reconfigured often, but that configuration data is rarely very large.

94. What platforms are supported in CouchDB?

Ans:

Most POSIX systems are supported like GNU/Linux and OS X. Window is not officially supported but it should work.

95. What is the use of sequences? How do you do sequences?

Ans:

Sequences are often used to ensure unique identifiers for each row in a database table. Sequences are hard to realize with replication. CouchDB generates unique ids from its own, and you can specify your own as well, so you don’t need a sequence here. If you use a sequence for something else, you might find a way to express in CouchDB in another way.

96. Is it possible to communicate to CouchDB without going through HTTP/ API?

Ans:

CouchDB’s data model and internal API map the REST/HTTP model in a very simple way that any other API would inherit some features of HTTP. However, there is a plan to refractor CouchDB’s internals to provide a documented Erlang API.

97. Differentiate between ETL Testing and Manual Testing?

Ans:

ETL testing is the basic procedure of writing scripts for the automated testing process, there is no need of any additional technical knowledge other than the software knows how. This testing is one of the fast and systematic testing that gives the top result.

Manual testing uses other testing and seeing the procedure and requires a technical knowledge of SQL and shell scripting. It is a time and efforts consuming procedure and is prone to errors.

98. What do you mean by cubes and OLAP cubes?

Ans:

• Cubes are the data processing units that comprise facts and dimensions from the database. Gives the multi-dimensional analysis.
• OLAP stands for Online Analytics processing and it stores a large amount of data in a multi-dimensional form that can be used for reporting purposes.

99. State the use of CouchDB?

Ans:

Uses of CouchDB are as stated;

• It can be used directly to write a client’s application without the use of any other server reducing the development time.
• It helps to replicate the database of the client and the filter feature helps to replicate the database of the specific user.

100. State few elements in Couchbase Node?

Ans:

Elements in Couchbase Nodes are;

• Index service
• Data service
• Cluster manager component
• Query service