Teradata Interview Questions and Answers

Ques 1. What is Teradata?

Teradata is a relational database management system (RDBMS) that is designed to handle large volumes of data and provide high performance in data warehousing and analytics.

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Ques 2. Explain the concept of Primary Index in Teradata.

Primary Index is used for distributing data across the AMPs (Access Module Processors) in a Teradata system. It determines the distribution of rows in a table based on the primary index value.

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Ques 3. What is the importance of the SET table in Teradata?

SET tables in Teradata eliminate duplicate rows, ensuring that each row is unique. They are useful in scenarios where you want to store distinct values.

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Ques 4. Explain the use of the COLLECT STATISTICS statement in Teradata.

The COLLECT STATISTICS statement is used to gather statistics on columns or indexes in a Teradata table. It helps the query optimizer make better decisions for query execution plans.

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Ques 5. Differentiate between INNER JOIN and LEFT JOIN in Teradata.

INNER JOIN returns only the matching rows from both tables, while LEFT JOIN returns all rows from the left table and the matching rows from the right table.

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Ques 6. Explain the use of the PARTITION BY clause in Teradata.

The PARTITION BY clause in Teradata is used in window functions to divide the result set into partitions to which the window function is applied separately. It is commonly used with functions like ROW_NUMBER() and RANK().

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Ques 7. Explain the purpose of the Teradata PRIMARY KEY constraint.

The PRIMARY KEY constraint in Teradata is used to uniquely identify each row in a table. It ensures that the values in the specified columns are unique and not NULL.

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Ques 8. Explain the use of the Teradata Aggregate Functions.

Teradata provides various aggregate functions like SUM, AVG, MIN, MAX, and COUNT to perform calculations on a set of values. These functions are commonly used in SELECT queries for summarizing data.

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Ques 9. Explain the concept of Vantage in Teradata.

Vantage is the modern analytics platform from Teradata that integrates data analytics, data lakes, and data warehouses. It allows users to analyze and derive insights from data stored in different environments.

Ques 10. Explain the purpose of the Teradata LOCKING modifier.

The LOCKING modifier in Teradata is used to specify the type of locks to be used during a query. It allows users to control the level of concurrency and the type of locks acquired on tables.

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Ques 11. Explain the Teradata INDEX constraints and their significance.

INDEX constraints in Teradata define the indexes on tables, specifying how data is physically organized. They are crucial for optimizing query performance by allowing the database to locate and retrieve data more efficiently.

Ques 12. What is the purpose of the BYNET in Teradata?

The BYNET (Binary Network) is a communication layer in Teradata that facilitates communication between AMPs and ensures the parallel processing of queries across multiple nodes in a Teradata system.

Ques 13. Explain the concept of MultiLoad in Teradata.

MultiLoad is a utility in Teradata used for efficiently loading, updating, or deleting large volumes of data from tables. It works by using multiple sessions to load or update data in parallel.

Ques 14. What are fallback and non-fallback options in Teradata?

Fallback and non-fallback are options for Teradata tables. Fallback means that a duplicate copy of each row is stored on a different AMP for fault tolerance, while non-fallback means there is no duplicate copy.

Ques 15. How does Teradata handle concurrency control?

Teradata uses a combination of locks and timestamps for concurrency control. It employs row-level locks and a two-phase locking protocol to manage concurrent access to data.

Ques 16. What is a Teradata Join Index, and when would you use it?

A Join Index in Teradata is a type of database object that is created to improve the performance of specific join queries. It precomputes and stores the result of a join operation to speed up query processing.

Ques 17. How does Teradata handle skewed tables, and what strategies can be used to address skewness?

Teradata uses various techniques such as hash redistributions and skewed join strategies to handle skewed tables. Skewness can be addressed by proper indexing, collecting statistics, and using appropriate join strategies.

Ques 18. What is Teradata's FastLoad utility, and when would you use it?

FastLoad is a Teradata utility used for fast loading of large volumes of data into an empty table. It bypasses the normal SQL processing and loads data directly into the target table, making it highly efficient for initial data loads.

Ques 19. What are the differences between Teradata and other database management systems like Oracle or SQL Server?

Teradata is designed for parallel processing and scalability in data warehousing, whereas other systems may have different focuses. Differences can include architecture, optimization techniques, and performance characteristics.

Ques 20. What is the Teradata Parallel Transporter (TPT), and how is it different from other utilities?

Teradata Parallel Transporter (TPT) is a comprehensive utility for loading, exporting, and managing data in Teradata. It is more flexible and extensible than traditional utilities like FastLoad and MultiLoad, providing better control over data movement.