Data Engineer Scenario Based Interview Questions

Why Hadoop Uses Context Object

Hadoop framework uses Context object with the Mapper class in order to interact with the remaining system. Context object gets the system configuration details and job in its constructor.

We use Context object in order to pass the information in setup, cleanup and map methods. This object makes vital information available during the map operations.

What Is The If Activity In The Azure Data Factory

If activity is used in the Azure data factory as a control activity. For example in some cases, you want to check whether steps to take or not based upon some condition. Then you can use if activity. You can pass the Boolean condition in the if activity and if it is true then it will take the step accordingly and if it is false then otherwise it will take the step accordingly.

How Can You Identify Missing Values In A Data Frame

The isnull function help to identify missing values in a given data frame.

The syntax is DataFrame.isnull

It returns a dataframe of boolean values of the same size as the data frame in which missing values are present. The missing values in the original data frame are mapped to true, and non-missing values are mapped to False.

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What Is The Use Of Metastore In Hive

Metastore is used as a storage location for the schema and Hive tables. Data such as definitions, mappings, and other metadata can be stored in the metastore. This is later stored in an RDMS when required.

Next up on this compilation of top Data Engineer interview questions, let us check out the advanced set of questions.

What Are The Various Types Of Load Balancers Available In Aws

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Can You Tell Me About Namenode What Happens If Namenode Crashes Or Comes To An End

It is the centre-piece or central node of the Hadoop Distributed File System, and it does not store actual data. It stores metadata. For example, the data being stored in DataNodes on which rack and which DataNode the information is stored. It tracks the different files present in clusters. Generally, there is one NameNode, so when it crashes, the system may not be available.

What Would You Do If Asked To Undertake Something Youd Never Done Before

Here the interviewer is testing your reliability and ability to adapt to changes in your work routine.

Sample Answer

If I need to take on a new task, I always start by clarifying any expectations. That provides a notion of where various priorities are and what is required in terms of results. After that, I assess the resources available.

Is there a knowledge bank or an on-demand training course available? Is there a coworker who has done this before and can provide advice? What assistance can I expect from my boss? Is there any research I can do on my own to fill in the gaps? I usually identify the route to success as I acquire knowledge from numerous sources.

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Behavioral Data Engineer Questions

Behavioral data engineer interview questions give the interviewer a chance to see how you have handled unforeseen data engineering issues or teamwork challenges in your experience. The answers you provide should reassure your future employer that you can deal with high-pressure situations and a variety of challenges. Here are a few examples to consider in your preparation.

12. Data maintenance is one of the routine responsibilities of a data engineer. Describe a time when you encountered an unexpected data maintenance problem that made you search for an out-of-the-box solution”.

How to Answer

Usually, data maintenance is scheduled and covers a particular task list. Therefore, when everything is operating according to plan, the tasks dont change as often. However, its inevitable that an unexpected issue arises every once in a while. As this might cause uncertainty on your end, the hiring manager would like to know how you would deal with such high-pressure situations.

Answer Example

Its true that data maintenance may come off as routine. But, in my opinion, its always a good idea to closely monitor the specified tasks. And that includes making sure the scripts are executed successfully. Once, while I was conducting an integrity check, I located a corrupt index that could have caused some serious problems in the future. This prompted me to come up with a new maintenance task that prevents corrupt indexes from being added to the companys databases.

How to Answer

Why Are You Interested In This Job And Why Should We Hire You

It is a fundamental data engineer interview question, but your answer can set you apart from the rest. To demonstrate your interest in the job, identify a few exciting features of the job, which makes it an excellent fit for you and then mention why you love the company.

For the second part of the question, link your skills, education, personality, and professional experience to the job and company culture. You can back your answers with examples from previous experience. As you justify your compatibility with the job and company, be sure to depict yourself as energetic, confident, motivated, and culturally fit for the company.

Start Your Career as a Big Data Engineer Today!

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Differentiate Between Star Schema And Snowflake Schema

What Is A Trigger In Sql

In SQL, a trigger refers to a set of statements in a system catalog that runs whenever DML commands run on a system. It is a special stored procedure that gets called automatically in response to an event. Triggers allow the execution of a batch of code whenever an insert, update or delete command is executed for a specific table. You can create a trigger by using the CREATE TRIGGER statement. The syntax is:

CREATE TRIGGER trigger_name

ON table_name FOR EACH ROW

BEGIN

END

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What Is Your Proudest Professional Accomplishment And How Did You Achieve It

Employers ask this question to learn about the sort of job you enjoy and the methods you take to achieve your objectives.

Sample Answer

In my prior work as an IT administrator, I discovered a security issue during my routine maintenance rounds. Rather than merely fixing it, I examined the network logs and discovered that a virus had recently compromised multiple files. I alerted the rest of the team, and we immediately isolated the infected files and blocked their spread, saving the organization millions of dollars. That experience fueled my desire to prevent cybercrime and prompted me to apply for this position as a cyber security manager.

How Does Orchestration Work

IT firms must manage a lot of servers and apps, but doing it manually isnt scalable. The more complicated an IT system is, the harder it is to keep track of all the moving elements. The demand to integrate several automated jobs and their configurations across groups of systems or machines is growing, coupled with the necessity to combine such automated operations and settings. This circumstance benefits from the usage of orchestration.

A computer system, application, and service orchestration is the automated configuration, administration, and coordination of these components. Orchestration makes it easier for IT to manage challenging operations and processes. Numerous technologies for container orchestration, including Kubernetes and OpenShift, are available.

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Give An Example Of When You Proposed Changes To Improve Data Reliability And Quality Did These Changes End Up Being Implemented If Not Why Not

How to Answer

Continuous improvement of the current environment is something hiring managers value. It is even more advantageous for you if these proposed changes were self-initiated and were not an assigned task, so be sure to highlight this if that is the case. This will display your ability to ‘think outside the box’ and the priority you place on quality of the company’s work overall. If you have never had an opportunity to propose changes to improve data reliability and quality, explain why you think it’s important and what you would do as a Data Engineer to ensure the data quality was always at a high level. In addition, if your proposed changes were not implemented for reasons such as lack of time or resources, go ahead and state that, but make sure you emphasize your continued commitment to finding new ways to improve data quality.

Written by Helen Lee on June 15th, 2018

Entry Level

“I believe that the work I produce is only as good as the data or evidence I have to back it up. That’s why it is important as a Data Engineer to continuously ensure that the data your company collects and relies on to make strategic decisions is clean and of high quality. If not, I need to help identify the issues and possible solutions to improve the data. As I work on any project, I am continually evaluating whether there is a more efficient or effective process to accomplish the task at hand.”

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What Are The 4 Most Key Questions A Data Engineer Is Likely To Hear During An Interview

The four most key questions a data engineer is likely to hear during an interview are

• What is data modeling?

• What are the four Vs of Big Data?

• Do you have any experience working on Hadoop, and how did you enjoy it?

• Do you have any experience working in a cloud computing environment, what are some challenges that you faced?

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What Happens When The Block Scanner Detects A Corrupt Data Block

The following steps occur when the block scanner detects a corrupt data block:

• First and foremost, when the Block Scanner detects a corrupted data block, DataNode notifies NameNode.
• NameNode begins the process of constructing a new replica from a corrupted block replica.
• The replication factor is compared to the replication count of the right replicas. The faulty data block will not be removed if a match is detected.

Mention Some Advantages Of Using Numpy Arrays Over Python Lists

• NumPy arrays take up less space in memory than lists.

• NumPy arrays are faster than lists.

• NumPy arrays have built-in functions optimized for various techniques such as linear algebra, vector, and matrix operations.

• Lists in Python do not allow element-wise operations, but NumPy arrays can perform element-wise operations.

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Which Programming/scripting Languages Do You Have Experience Utilizing Which One Do You Have The Most Experience With

How to Answer

In most cases, job descriptions will outline which programming language skills are preferred or required for the job, so going into the interview you should have this information if it was made available to you. Specify which language you have the most experience with, but circle back to the preferred/required programming language if you have used it/them in past projects so you at least let the interviewer know you have had some exposure to it.If you do not have experience with it/those, the hiring manager must have found other valuable aspects of your resume that would be beneficial to the job. If this is the case for you, concentrate your answer on the language you have the most experience with and highlight any similarities it may have to the required or preferred language. In addition, highlight any strengths you may have with learning new concepts or languages. You want to convey to the interviewer that you will be dedicated to working with the systems and programs that the company has in place, even if it requires additional training.

Written by Helen Lee on June 15th, 2018

Entry Level

“The languages I have had the most exposure to are SQL, Java, R and Python. I am most comfortable using SQL since this is the language I have used most often in various school class projects. However, I enjoy expanding my programming knowledge base by learning new languages. I realize that sometimes one programming language may not be the best solution in every scenario.”

Top 29 Data Engineer Interview Questions And Answers

List of Most Frequently Asked Data Engineer Interview Questions And Answers to Help You Prepare For The Upcoming Interview:

Today, data engineering is the most sought after field after software development and it has become one of the fastest-growing job options in the world. Interviewers want the best data engineers for their team and thats why they tend to interview the candidates thoroughly. They look for certain skills and knowledge. So, you have to be prepared accordingly to meet their expectations.

What You Will Learn:

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Which Python Libraries Would You Recommend For Effective Data Processing

This question allows the hiring manager to determine whether the candidate understands the fundamentals of Python, which is the most commonly used language among data engineers. NumPy, which is used for efficient processing of arrays of numbers, and pandas, which is useful for statistics and data preparation for machine learning work, should be included in your solution.

Using The Following Sql Table Definitions And Data How Would You Construct A Query That Shows

A data engineer needs to be able to construct and execute queries in order to understand the existing data, and to verify data transformations that are part of the data pipeline.

You can ask a few questions covering SQL to ensure the data engineer candidate has a good handle on the query language.

Here are some examples:

• With a product table defined with a name, SKU, and price, how would you construct a query that shows the lowest priced item?
• With an order table defined with a date, a product SKU, price, quantity, tax rate, and shipping rate, how would you construct a query that shows the average order cost?

You can use the SQL below to setup the examples above:

CREATE TABLE products  NOT NULL,  price DECIMAL NOT NULL,  PRIMARY KEY) CREATE TABLE orders  NOT NULL,  quantity INT NOT NULL,  tax_rate DECIMAL NOT NULL,  shipping_rate DECIMAL NOT NULL,  FOREIGN KEY REFERENCES products) INSERT INTO products VALUES  INSERT INTO products VALUES  INSERT INTO orders VALUES  INSERT INTO orders VALUES  

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What Is The Azure Data Factory Service

Azure Data factory is the service that helps you to do the migrations and orchestrate the work. For example, if you want to move the data from on-premise to cloud, maybe it is incremental or it will be lift and shift work there you can leverage the Azure Data factory to do the work. It support around hundred of the different data sources from which we can pull the data.

Mention Some Of Hadoop’s Key Attributes

• Hadoop is a free, open-source framework whose code can be modified to suit different needs.
• It supports faster-distributed data processing with MapReduce.
• Hadoop is quite forgiving and, by default, permits the user to build three clones of each block at several nodes. Therefore, even if one of the nodes fails, we may still recover the data from another node.
• Scalable and hardware-neutral.
• Due to Hadoop’s cluster-based data storage, all other operations were unaffected. Thus, it is trustworthy. The failure of the machines has no impact on the data that has been stored.

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Do You Have Prior Experience Working With Data Modeling

If you are interviewed for an intermediate-level role, this is a question that you will always be asked. Begin your answer with a simple yes or no. It is alright if you have not worked with data modeling before, but make sure to explain whatever you know about data modeling in a concise and structured manner. It would be advantageous if you have used tools like Pentaho or Informatica for this purpose.

If you are looking forward to learning and mastering all of the Data Analytics and Data Science concepts and earning a certification in the same, do take a look at Intellipaats latest Data Science with R Certification offerings.

Basic Big Data Hadoop Interview Questions

Hadoop is one of the most popular Big Data frameworks, and if you are going for a Hadoop interview prepare yourself with these basic level interview questions for Big Data Hadoop. These questions will be helpful for you whether you are going for a Hadoop developer or Hadoop Admin interview.

21. Explain the difference between Hadoop and RDBMS.

Answer: The difference between Hadoop and RDBMS is as follows 22. What are the common input formats in Hadoop?

Answer: Below are the common input formats in Hadoop

• Text Input Format The default input format defined in Hadoop is the Text Input Format.
• Sequence File Input Format To read files in a sequence, Sequence File Input Format is used.
• Key Value Input Format The input format used for plain text files is the Key Value Input Format.

23. Explain some important features of Hadoop.

Answer: Hadoop supports the storage and processing of big data. It is the best solution for handling big data challenges. Some important features of Hadoop are

24. Explain the different modes in which Hadoop run.

Answer: Apache Hadoop runs in the following three modes

25. Explain the core components of Hadoop.

Answer: Hadoop is an open source framework that is meant for storage and processing of big data in a distributed manner. The core components of Hadoop are

Core Components of Hadoop

26. What are the configuration parameters in a MapReduce program?

The main configuration parameters in MapReduce framework are:

• ResourceManager

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