TCS Data Engineer Interview Questions and Answers

Reverse strings in a Python list

• Use list comprehension to iterate through the list and reverse each string

• Use the slice notation [::-1] to reverse each string

• Example: strings = ['hello', 'world'], reversed_strings = [s[::-1] for s in strings]

To find the 2nd highest salary in SQL, use the 'SELECT' statement with 'ORDER BY' and 'LIMIT' clauses.

• Use the 'SELECT' statement to retrieve the salary column from the table.

• Use the 'ORDER BY' clause to sort the salaries in descending order.

• Use the 'LIMIT' clause to limit the result to the second row.

SCD 1 overwrites old data with new data, while SCD 2 keeps track of historical changes.

• SCD 1 updates existing records with new data, losing historical information.

• SCD 2 creates new records for each change, preserving historical data.

• SCD 1 is simpler and faster, but can lead to data loss.

• SCD 2 is more complex and slower, but maintains a full history of changes.

Corrupt record handling in Spark involves identifying and handling data that does not conform to expected formats.

• Use DataFrameReader option("badRecordsPath", "path/to/bad/records") to save corrupt records to a separate location for further analysis.

• Use DataFrame.na.drop() or DataFrame.na.fill() to handle corrupt records by dropping or filling missing values.

• Implement custom logic to identify and handle corrupt records...read more

Object-oriented programming (OOP) is a programming paradigm based on the concept of objects, which can contain data in the form of fields and code in the form of procedures.

• OOP focuses on creating objects that interact with each other to solve a problem

• Key concepts include encapsulation, inheritance, polymorphism, and abstraction

• Encapsulation involves bundling data and methods that operate on the data into a single uni...read more

Data engineer life cycle involves collecting, storing, processing, and analyzing data using various tools.

• Data collection: Gathering data from various sources such as databases, APIs, and logs.

• Data storage: Storing data in databases, data lakes, or data warehouses.

• Data processing: Cleaning, transforming, and enriching data using tools like Apache Spark or Hadoop.

• Data analysis: Analyzing data to extract insights and mak...read more

Spark join strategies include broadcast join, shuffle hash join, and shuffle sort merge join.

• Broadcast join is used when one of the DataFrames is small enough to fit in memory on all nodes.

• Shuffle hash join is used when joining two large DataFrames by partitioning and shuffling the data based on the join key.

• Shuffle sort merge join is used when joining two large DataFrames by sorting and merging the data based on the j...read more

Spark is a fast and general-purpose cluster computing system for big data processing.

• Spark is popular for its speed and ease of use in processing large datasets.

• It provides in-memory processing capabilities, making it faster than traditional disk-based processing systems.

• Spark supports multiple programming languages like Java, Scala, Python, and R.

• It offers a wide range of libraries for diverse tasks such as SQL, strea...read more

Clustering is the process of grouping similar data points together. Pods are groups of one or more containers, while nodes are individual machines in a cluster.

• Clustering is a technique used in machine learning to group similar data points together based on certain features or characteristics.

• Pods in a cluster are groups of one or more containers that share resources and are scheduled together on the same node.

• Nodes ar...read more