Data Engineers

Planning for Data Engineering Interview. Focus on SQL & Python first. Here are some important questions which you should know. 𝐈𝐦𝐩𝐨𝐫𝐭𝐚𝐧𝐭 𝐒𝐐𝐋 𝐪𝐮𝐞𝐬𝐭𝐢𝐨𝐧𝐬 1- Find out nth Order/Salary from the tables. 2- Find the no of output records in each join from given Table 1 & Table 2 3- YOY,MOM Growth related questions. 4- Find out Employee ,Manager Hierarchy (Self join related question) or Employees who are earning more than managers. 5- RANK,DENSERANK related questions 6- Some row level scanning medium to complex questions using CTE or recursive CTE, like (Missing no /Missing Item from the list etc.) 7- No of matches played by every team or Source to Destination flight combination using CROSS JOIN. 8-Use window functions to perform advanced analytical tasks, such as calculating moving averages or detecting outliers. 9- Implement logic to handle hierarchical data, such as finding all descendants of a given node in a tree structure. 10-Identify and remove duplicate records from a table. 𝐈𝐦𝐩𝐨𝐫𝐭𝐚𝐧𝐭 𝐏𝐲𝐭𝐡𝐨𝐧 𝐪𝐮𝐞𝐬𝐭𝐢𝐨𝐧𝐬 1- Reversing a String using an Extended Slicing techniques. 2- Count Vowels from Given words . 3- Find the highest occurrences of each word from string and sort them in order. 4- Remove Duplicates from List. 5-Sort a List without using Sort keyword. 6-Find the pair of numbers in this list whose sum is n no. 7-Find the max and min no in the list without using inbuilt functions. 8-Calculate the Intersection of Two Lists without using Built-in Functions 9-Write Python code to make API requests to a public API (e.g., weather API) and process the JSON response. 10-Implement a function to fetch data from a database table, perform data manipulation, and update the database. Data Engineering Interview Preparation Resources: https://topmate.io/analyst/910180 All the best 👍👍

Cisco Kafka interview questions for Data Engineers 2024. ➤ How do you create a topic in Kafka using the Confluent CLI? ➤ Explain the role of the Schema Registry in Kafka. ➤ How do you register a new schema in the Schema Registry? ➤ What is the importance of key-value messages in Kafka? ➤ Describe a scenario where using a random key for messages is beneficial. ➤ Provide an example where using a constant key for messages is necessary. ➤ Write a simple Kafka producer code that sends JSON messages to a topic. ➤ How do you serialize a custom object before sending it to a Kafka topic? ➤ Describe how you can handle serialization errors in Kafka producers. ➤ Write a Kafka consumer code that reads messages from a topic and deserializes them from JSON. ➤ How do you handle deserialization errors in Kafka consumers? ➤ Explain the process of deserializing messages into custom objects. ➤ What is a consumer group in Kafka, and why is it important? ➤ Describe a scenario where multiple consumer groups are used for a single topic. ➤ How does Kafka ensure load balancing among consumers in a group? ➤ How do you send JSON data to a Kafka topic and ensure it is properly serialized? ➤ Describe the process of consuming JSON data from a Kafka topic and converting it to a usable format. ➤ Explain how you can work with CSV data in Kafka, including serialization and deserialization. ➤ Write a Kafka producer code snippet that sends CSV data to a topic. ➤ Write a Kafka consumer code snippet that reads and processes CSV data from a topic. Data Engineering Interview Preparation Resources: https://topmate.io/analyst/910180 All the best 👍👍

𝐇𝐞𝐫𝐞 𝐚𝐫𝐞 20 𝐫𝐞𝐚𝐥-𝐭𝐢𝐦𝐞 𝐒𝐩𝐚𝐫𝐤 𝐬𝐜𝐞𝐧𝐚𝐫𝐢𝐨-𝐛𝐚𝐬𝐞𝐝 𝐪𝐮𝐞𝐬𝐭𝐢𝐨𝐧𝐬 1. Data Processing Optimization: How would you optimize a Spark job that processes 1 TB of data daily to reduce execution time and cost? 2. Handling Skewed Data: In a Spark job, one partition is taking significantly longer to process due to skewed data. How would you handle this situation? 3. Streaming Data Pipeline: Describe how you would set up a real-time data pipeline using Spark Structured Streaming to process and analyze clickstream data from a website. 4. Fault Tolerance: How does Spark handle node failures during a job, and what strategies would you use to ensure data processing continues smoothly? 5. Data Join Strategies: You need to join two large datasets in Spark, but you encounter memory issues. What strategies would you employ to handle this? 6. Checkpointing: Explain the role of checkpointing in Spark Streaming and how you would implement it in a real-time application. 7. Stateful Processing: Describe a scenario where you would use stateful processing in Spark Streaming and how you would implement it. 8. Performance Tuning: What are the key parameters you would tune in Spark to improve the performance of a real-time analytics application? 9. Window Operations: How would you use window operations in Spark Streaming to compute rolling averages over a sliding window of events? 10. Handling Late Data: In a Spark Streaming job, how would you handle late-arriving data to ensure accurate results? 11. Integration with Kafka: Describe how you would integrate Spark Streaming with Apache Kafka to process real-time data streams. 12. Backpressure Handling: How does Spark handle backpressure in a streaming application, and what configurations can you use to manage it? 13. Data Deduplication: How would you implement data deduplication in a Spark Streaming job to ensure unique records? 14. Cluster Resource Management: How would you manage cluster resources effectively to run multiple concurrent Spark jobs without contention? 15. Real-Time ETL: Explain how you would design a real-time ETL pipeline using Spark to ingest, transform, and load data into a data warehouse. 16. Handling Large Files: You have a #Spark job that needs to process very large files (e.g., 100 GB). How would you optimize the job to handle such files efficiently? 17. Monitoring and Debugging: What tools and techniques would you use to monitor and debug a Spark job running in production? 18. Delta Lake: How would you use Delta Lake with Spark to manage real-time data lakes and ensure data consistency? 19. Partitioning Strategy: How you would design an effective partitioning strategy for a large dataset. 20. Data Serialization: What serialization formats would you use in Spark for real-time data processing, and why? Data Engineering Interview Preparation Resources: https://topmate.io/analyst/910180 All the best 👍👍

Preparing for a Spark Interview? Here are 20 Key Differences You Should Know! 1️⃣ Repartition vs. Coalesce: Repartition changes the number of partitions, while coalesce reduces partitions without full shuffle. 2️⃣ Sort By vs. Order By: Sort By sorts data within each partition and may result in partially ordered final results if multiple reducers are used. Order By guarantees total order across all partitions in the final output. 3️⃣ RDD vs. Datasets vs. DataFrames: RDDs are the basic abstraction, Datasets add type safety, and DataFrames optimize for structured data. 4️⃣ Broadcast Join vs. Shuffle Join vs. Sort Merge Join: Broadcast Join is for small tables, Shuffle Join redistributes data, and Sort Merge Join sorts data before joining. 5️⃣ Spark Session vs. Spark Context: Spark Session is the entry point in Spark 2.0+, combining functionality of Spark Context and SQL Context. 6️⃣ Executor vs. Executor Core: Executor runs tasks and manages data storage, while Executor Core handles task execution. 7️⃣ DAG vs. Lineage: DAG (Directed Acyclic Graph) is the execution plan, while Lineage tracks the RDD lineage for fault tolerance. 8️⃣ Transformation vs. Action: Transformation creates RDD/Dataset/DataFrame, while Action triggers execution and returns results to driver. 9️⃣ Narrow Transformation vs. Wide Transformation: Narrow operates on single partition, while Wide involves shuffling across partitions. 🔟 Lazy Evaluation vs. Eager Evaluation: Spark delays execution until action is called (Lazy), optimizing performance. 1️⃣1️⃣ Window Functions vs. Group By: Window Functions compute over a range of rows, while Group By aggregates data into summary. 1️⃣2️⃣ Partitioning vs. Bucketing: Partitioning divides data into logical units, while Bucketing organizes data into equal-sized buckets. 1️⃣3️⃣ Avro vs. Parquet vs. ORC: Avro is row-based with schema, Parquet and ORC are columnar formats optimized for query speed. 1️⃣4️⃣ Client Mode vs. Cluster Mode: Client runs driver in client process, while Cluster deploys driver to the cluster. 1️⃣5️⃣ Serialization vs. Deserialization: Serialization converts data to byte stream, while Deserialization reconstructs data from byte stream. 1️⃣6️⃣ DAG Scheduler vs. Task Scheduler: DAG Scheduler divides job into stages, while Task Scheduler assigns tasks to workers. 1️⃣7️⃣ Accumulators vs. Broadcast Variables: Accumulators aggregate values from workers to driver, Broadcast Variables efficiently broadcast read-only variables. 1️⃣8️⃣ Cache vs. Persist: Cache stores RDD/Dataset/DataFrame in memory, Persist allows choosing storage level (memory, disk, etc.). 1️⃣9️⃣ Internal Table vs. External Table: Internal managed by Spark, External managed externally (e.g., Hive). 2️⃣0️⃣ Executor vs. Driver: Executor runs tasks on worker nodes, Driver manages job execution. Data Engineering Interview Preparation Resources: https://topmate.io/analyst/910180 All the best 👍👍

Complete Python topics required for the Data Engineer role: ➤ 𝗕𝗮𝘀𝗶𝗰𝘀 𝗼𝗳 𝗣𝘆𝘁𝗵𝗼𝗻: - Python Syntax - Data Types - Lists - Tuples - Dictionaries - Sets - Variables - Operators - Control Structures: - if-elif-else - Loops - Break & Continue try-except block - Functions - Modules & Packages ➤ 𝗣𝗮𝗻𝗱𝗮𝘀: - What is Pandas & imports? - Pandas Data Structures (Series, DataFrame, Index) - Working with DataFrames: -> Creating DFs -> Accessing Data in DFs Filtering & Selecting Data -> Adding & Removing Columns -> Merging & Joining in DFs -> Grouping and Aggregating Data -> Pivot Tables - Input/Output Operations with Pandas: -> Reading & Writing CSV Files -> Reading & Writing Excel Files -> Reading & Writing SQL Databases -> Reading & Writing JSON Files -> Reading & Writing - Text & Binary Files ➤ 𝗡𝘂𝗺𝗽𝘆: - What is NumPy & imports? - NumPy Arrays - NumPy Array Operations: - Creating Arrays - Accessing Array Elements - Slicing & Indexing - Reshaping, Combining & Arrays - Arithmetic Operations - Broadcasting - Mathematical Functions - Statistical Functions ➤ 𝗕𝗮𝘀𝗶𝗰𝘀 𝗼𝗳 𝗣𝘆𝘁𝗵𝗼𝗻, 𝗣𝗮𝗻𝗱𝗮𝘀, 𝗡𝘂𝗺𝗽𝘆 are more than enough for Data Engineer role. Data Engineering Interview Preparation Resources: https://topmate.io/analyst/910180 All the best 👍👍

𝗪𝗮𝗻𝘁 𝘁𝗼 𝗯𝗲𝗰𝗼𝗺𝗲 𝗮 𝗗𝗮𝘁𝗮 𝗘𝗻𝗴𝗶𝗻𝗲𝗲𝗿? Here is a complete week-by-week roadmap that can help 𝗪𝗲𝗲𝗸 𝟭: Learn programming - Python for data manipulation, and Java for big data frameworks. 𝗪𝗲𝗲𝗸 𝟮-𝟯: Understand database concepts and databases like MongoDB. 𝗪𝗲𝗲𝗸 𝟰-𝟲: Start with data warehousing (ETL), Big Data (Hadoop) and Data pipelines (Apache AirFlow) 𝗪𝗲𝗲𝗸 𝟲-𝟴: Go for advanced topics like cloud computing and containerization (Docker). 𝗪𝗲𝗲𝗸 𝟵-𝟭𝟬: Participate in Kaggle competitions, build projects and develop communication skills. 𝗪𝗲𝗲𝗸 𝟭𝟭: Create your resume, optimize your profiles on job portals, seek referrals and apply. Data Engineering Interview Preparation Resources: https://topmate.io/analyst/910180 All the best 👍👍

Data Engineering is not Excel. Not writing ML models. Not “please can you do this quick? I need it asap”

Life of a Data Engineer..... Business user : Can we add a filter on this dashboard. This will help us track a critical metric. me : sure this should be a quick one. Next day : I quickly opened the dashboard to find the column in the existing dashboard's data sources. -- column not found Spent a couple of hours to identify the data source and how to bring the column into the existence data pipeline which feeds the dashboard( table granularity , join condition etc..). Then comes the pipeline changes , data model changes , dashboard changes , validation/testing. Finally deploying to production and a simple email to the user that the filter has been added. A small change in the front end but a lot of work in the backend to bring that column to life. Never underestimate data engineers and data pipelines 💪

The number one thing to do as a data engineer? Create high-quality data that people can trust.🤝

Learning SQL is actually a really good skill. It's not just learning SQL the language, but learning the concepts of relational algebra and how to think about data sets, designing schemas, and organizing data. ... It is about learning the file formatting and the basics of data storage, data partitioning, and the relationship between the execution engines. All of these things will yield you to be a better DBT user, a better Snowflake user or a Databricks user.

Here are 15 basic Linux commands you must know before starting your first full-time job or internship. Save this post for later. 1. How to create a new directory? A: mkdir 2. How to create new files? A: touch 3. How to print the current directory that you are in? A: pwd 4. How to list the contents of a directory? A: ls 5. How to move to a different directory? A: cd 6. How to preview the content of a file? A: cat 7. How to see the history of commands that you've used previously? A: history 8. How to search a pattern of text within a directory (dfs the whole subtree) using a regular expression? A: grep 9. How to stop a running process using it's process id? A: kill 10. How to change the permission of a file and directory? A: chmod 11. How to replace occurrences in a file? A: sed 12. How to output something on terminal (usually from inside of a scripts) A: echo 13. How to display the beginning for a text file? A: head 14. How to display the end of a text file? A: tail 15. How to copy files and directories? A: cp Data Engineering Interview Preparation Resources: https://topmate.io/analyst/910180 All the best 👍👍

Thinking about becoming a Data Engineer? Here's the roadmap to avoid pitfalls & master the essential skills for a successful career. 📊Introduction to Data Engineering ✅Overview of Data Engineering & its importance ✅Key responsibilities & skills of a Data Engineer ✅Difference between Data Engineer, Data Scientist & Data Analyst ✅Data Engineering tools & technologies 📊Programming for Data Engineering ✅Python ✅SQL ✅Java/Scala ✅Shell scripting 📊Database System & Data Modeling ✅Relational Databases: design, normalization & indexing ✅NoSQL Databases: key-value stores, document stores, column-family stores & graph database ✅Data Modeling: conceptual, logical & physical data model ✅Database Management Systems & their administration 📊Data Warehousing and ETL Processes ✅Data Warehousing concepts: OLAP vs. OLTP, star schema & snowflake schema ✅ETL: designing, developing & managing ETL processe ✅Tools & technologies: Apache Airflow, Talend, Informatica, AWS Glue ✅Data lakes & modern data warehousing solution 📊Big Data Technologies ✅Hadoop ecosystem: HDFS, MapReduce, YARN ✅Apache Spark: core concepts, RDDs, DataFrames & SparkSQL ✅Kafka and real-time data processing ✅Data storage solutions: HBase, Cassandra, Amazon S3 📊Cloud Platforms & Services ✅Introduction to cloud platforms: AWS, Google Cloud Platform, Microsoft Azure ✅Cloud data services: Amazon Redshift, Google BigQuery, Azure Data Lake ✅Data storage & management on the cloud ✅Serverless computing & its applications in data engineering 📊Data Pipeline Orchestration ✅Workflow orchestration: Apache Airflow, Luigi, Prefect ✅Building & scheduling data pipelines ✅Monitoring & troubleshooting data pipelines ✅Ensuring data quality & consistency 📊Data Integration & API Development ✅Data integration techniques & best practices ✅API development: RESTful APIs, GraphQL ✅Tools for API development: Flask, FastAPI, Django ✅Consuming APIs & data from external sources 📊Data Governance & Security ✅Data governance frameworks & policies ✅Data security best practices ✅Compliance with data protection regulations ✅Implementing data auditing & lineage 📊Performance Optimization & Troubleshooting ✅Query optimization techniques ✅Database tuning & indexing ✅Managing & scaling data infrastructure ✅Troubleshooting common data engineering issues 📊Project Management & Collaboration ✅Agile methodologies & best practices ✅Version control systems: Git & GitHub ✅Collaboration tools: Jira, Confluence, Slack ✅Documentation & reporting Resources for Data Engineering 1️⃣Python: https://t.me/pythonanalyst 2️⃣SQL: https://t.me/sqlanalyst 3️⃣Excel: https://t.me/excel_analyst 4️⃣Free DE Courses: https://t.me/free4unow_backup/569 Data Engineering Interview Preparation Resources: https://topmate.io/analyst/910180 All the best 👍👍

DevOps Tech Stack

Planning for Data Science or Data Engineering Interview. Focus on SQL & Python first. Here are some important questions which you should know. 𝐈𝐦𝐩𝐨𝐫𝐭𝐚𝐧𝐭 𝐒𝐐𝐋 𝐪𝐮𝐞𝐬𝐭𝐢𝐨𝐧𝐬 1- Find out nth Order/Salary from the tables. 2- Find the no of output records in each join from given Table 1 & Table 2 3- YOY,MOM Growth related questions. 4- Find out Employee ,Manager Hierarchy (Self join related question) or Employees who are earning more than managers. 5- RANK,DENSERANK related questions 6- Some row level scanning medium to complex questions using CTE or recursive CTE, like (Missing no /Missing Item from the list etc.) 7- No of matches played by every team or Source to Destination flight combination using CROSS JOIN. 8-Use window functions to perform advanced analytical tasks, such as calculating moving averages or detecting outliers. 9- Implement logic to handle hierarchical data, such as finding all descendants of a given node in a tree structure. 10-Identify and remove duplicate records from a table. SQL Interview Resources: https://topmate.io/analyst/864764 𝐈𝐦𝐩𝐨𝐫𝐭𝐚𝐧𝐭 𝐏𝐲𝐭𝐡𝐨𝐧 𝐪𝐮𝐞𝐬𝐭𝐢𝐨𝐧𝐬 1- Reversing a String using an Extended Slicing techniques. 2- Count Vowels from Given words . 3- Find the highest occurrences of each word from string and sort them in order. 4- Remove Duplicates from List. 5-Sort a List without using Sort keyword. 6-Find the pair of numbers in this list whose sum is n no. 7-Find the max and min no in the list without using inbuilt functions. 8-Calculate the Intersection of Two Lists without using Built-in Functions 9-Write Python code to make API requests to a public API (e.g., weather API) and process the JSON response. 10-Implement a function to fetch data from a database table, perform data manipulation, and update the database. Python Interview Resources: https://topmate.io/analyst/907371 Join for more: https://t.me/datasciencefun ENJOY LEARNING 👍👍

Frequently asked SQL interview questions for Data Analyst/Data Engineer role- 1 - What is SQL and what are its main features? 2 - Order of writing SQL query? 3- Order of execution of SQL query? 4- What are some of the most common SQL commands? 5- What’s a primary key & foreign key? 6 - All types of joins and questions on their outputs? 7 - Explain all window functions and difference between them? 8 - What is stored procedure? 9 - Difference between stored procedure & Functions in SQL? 10 - What is trigger in SQL? 11 - Difference between where and having?

Complete topics & subtopics of #SQL for Data Engineer role:- 𝟭. 𝗕𝗮𝘀𝗶𝗰 𝗦𝗤𝗟 𝗦𝘆𝗻𝘁𝗮𝘅: SQL keywords Data types Operators SQL statements (SELECT, INSERT, UPDATE, DELETE) 𝟮. 𝗗𝗮𝘁𝗮 𝗗𝗲𝗳𝗶𝗻𝗶𝘁𝗶𝗼𝗻 𝗟𝗮𝗻𝗴𝘂𝗮𝗴𝗲 (𝗗𝗗𝗟): CREATE TABLE ALTER TABLE DROP TABLE Truncate table 𝟯. 𝗗𝗮𝘁𝗮 𝗠𝗮𝗻𝗶𝗽𝘂𝗹𝗮𝘁𝗶𝗼𝗻 𝗟𝗮𝗻𝗴𝘂𝗮𝗴𝗲 (𝗗𝗠𝗟): SELECT statement (SELECT, FROM, WHERE, ORDER BY, GROUP BY, HAVING, JOINs) INSERT statement UPDATE statement DELETE statement 𝟰. 𝗔𝗴𝗴𝗿𝗲𝗴𝗮𝘁𝗲 𝗙𝘂𝗻𝗰𝘁𝗶𝗼𝗻𝘀: SUM, AVG, COUNT, MIN, MAX GROUP BY clause HAVING clause 𝟱. 𝗗𝗮𝘁𝗮 𝗖𝗼𝗻𝘀𝘁𝗿𝗮𝗶𝗻𝘁𝘀: Primary Key Foreign Key Unique NOT NULL CHECK 𝟲. 𝗝𝗼𝗶𝗻𝘀: INNER JOIN LEFT JOIN RIGHT JOIN FULL OUTER JOIN Self Join Cross Join 𝟳. 𝗦𝘂𝗯𝗾𝘂𝗲𝗿𝗶𝗲𝘀: Types of subqueries (scalar, column, row, table) Nested subqueries Correlated subqueries 𝟴. 𝗔𝗱𝘃𝗮𝗻𝗰𝗲𝗱 𝗦𝗤𝗟 𝗙𝘂𝗻𝗰𝘁𝗶𝗼𝗻𝘀: String functions (CONCAT, LENGTH, SUBSTRING, REPLACE, UPPER, LOWER) Date and time functions (DATE, TIME, TIMESTAMP, DATEPART, DATEADD) Numeric functions (ROUND, CEILING, FLOOR, ABS, MOD) Conditional functions (CASE, COALESCE, NULLIF) 𝟵. 𝗩𝗶𝗲𝘄𝘀: Creating views Modifying views Dropping views 𝟭𝟬. 𝗜𝗻𝗱𝗲𝘅𝗲𝘀: Creating indexes Using indexes for query optimization 𝟭𝟭. 𝗧𝗿𝗮𝗻𝘀𝗮𝗰𝘁𝗶𝗼𝗻𝘀: ACID properties Transaction management (BEGIN, COMMIT, ROLLBACK, SAVEPOINT) Transaction isolation levels 𝟭𝟮. 𝗗𝗮𝘁𝗮 𝗜𝗻𝘁𝗲𝗴𝗿𝗶𝘁𝘆 𝗮𝗻𝗱 𝗦𝗲𝗰𝘂𝗿𝗶𝘁𝘆: Data integrity constraints (referential integrity, entity integrity) GRANT and REVOKE statements (granting and revoking permissions) Database security best practices 𝟭𝟯. 𝗦𝘁𝗼𝗿𝗲𝗱 𝗣𝗿𝗼𝗰𝗲𝗱𝘂𝗿𝗲𝘀 𝗮𝗻𝗱 𝗙𝘂𝗻𝗰𝘁𝗶𝗼𝗻𝘀: Creating stored procedures Executing stored procedures Creating functions Using functions in queries 𝟭𝟰. 𝗣𝗲𝗿𝗳𝗼𝗿𝗺𝗮𝗻𝗰𝗲 𝗢𝗽𝘁𝗶𝗺𝗶𝘇𝗮𝘁𝗶𝗼𝗻: Query optimization techniques (using indexes, optimizing joins, reducing subqueries) Performance tuning best practices 𝟭𝟱. 𝗔𝗱𝘃𝗮𝗻𝗰𝗲𝗱 𝗦𝗤𝗟 𝗖𝗼𝗻𝗰𝗲𝗽𝘁𝘀: Recursive queries Pivot and unpivot operations Window functions (Row_number, rank, dense_rank, lead & lag) CTEs (Common Table Expressions) Dynamic SQL Here you can find quick SQL Revision Notes👇 https://topmate.io/analyst/864817 Like for more Hope it helps :)