Introduction to Teradata Interview Questions and Answers

Teradata is referred to as a Relational database management system (RDBMS) that is used to drive large Datawarehouse applications. Teradata was founded in the year 1979, and its headquarters is in San Diego, California. Teradata is capable of running the single and multi-nodes as well. The main concept behind Teradata is parallelism.

Teradata follows the architecture of shared-nothing architecture. Teradata nodes, its access module processors, and the risks associated with it independently. This database system is mainly based on Massively parallel processing architecture. It divides the workload evenly to an entire system. It automatically distributes the data to the disks without any manual intervention. It divides the task among the processes and runs in parallel to make sure that they should get completed quickly or timely. Its systems are mainly highly scalable, which can help to increase the nodes. Teradata is getting popular these days, and resources are required for this technology.

If you are looking for a job related to Teradata, you need to prepare for the 2020 Teradata Interview Questions. Every interview is indeed different as per the different job profiles. Here, we have prepared the important Teradata Interview Questions and Answers, which will help you succeed in your interview.

This 2020 Teradata Interview Questions article will present the 10 most important and frequently used Teradata interview questions. These questions will help students build their concepts around Teradata and help them ace the interview.

Part 1 – Teradata Interview Questions (Basic)

This first part covers basic Interview Questions and Answers.

Q1. Define Teradata and its new features developed?

Answer:
Teradata is RDBMS that is mainly suitable for building large-scale data warehousing applications. It has been built on a concept of parallelism. It acts in the way of the server, and it is an open system. Some new features are automated temporal analytics, a customer associated innovation like Teradata viewpoint, and a most important feature is providing the extension in compression capabilities that allows compression of data way more than earlier versions.

Q2. Explain the different table types; which Teradata supports?

Answer:
Find below the different tables that Teradata supports are:

Permanent Table: These tables are default table types supported by Teradata, mainly used to store the data in a Teradata system permanently.
Derived table: These tables have less lifetime. It is mainly there during the query’s execution time. It mainly holds the intermediate results of the query while execution.
Volatile table: These tables are used to store the data only during the user session. These tables are mainly used when we need to store the intermediate data during the complex calculations or any sharing or transmitting of data. These tables mainly delete the data after the end of the user’s session.
Global Temporary table: This table is used to store the values globally used in the applications, and this table will delete the data after the end of the user session.

Q3. Explain the main components of the Teradata system?

Answer:
Please find below the major components of the Teradata system:

Access Module Processor (AMP): It is used to store the actual data and retrieve the Teradata system agent. AMP helps to read and write the data to disks or location where the data has been stored physically.
Message Passing layer (MPL): It is referred to as a networking layer in the Teradata system. It is mainly used for the communication between the Access module processor, nodes, and parsing engine.
Nodes: In the Teradata system, a node is referred to as the individual server and basic unit for the system. The node mainly consists of its own copy of the operating system, CPU, memory, disk space, and RDBMS (belongs to Teradata).
Parsing engine: This engine is used for receiving the request from the client-server and create the execution plan accordingly. It provides some features like receiving the request and checking the syntax errors, verifying the user access to execute the SQL query, verifying the availability of objects associated with the SQL query, and preparing the execution plan and SQL query receives the result and sends the it across.

Q4. Which ETL tools come under Teradata?

Answer:
Informatica, SSIS, and data stage are common ETL tools used in Teradata.

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Q5. Explain briefly about the primary index in Teradata?

Answer:
The primary index is the mechanism that specifies where the data resides in a Teradata system. It’s mandatory in Teradata that each table has the primary index specified. Teradata can assign the primary index for the table if it’s not specified, as the primary index provides faster access to data. Unique primary index and non-unique primary index are the two types f primary indexes.

Part 2 – Teradata Interview Questions (Advanced)

Let us now have a look at the advanced Interview Questions.

Q6. Explain the difference between a primary index and the primary key?

Answer:
In Teradata, a Primary index is referred to as mandatory for the table, whereas the primary key can be optional. The primary Key does not have any limits to tables and columns, whereas the primary index has a limit of 64 tables or columns. The primary index is the physical mechanism, and it allows duplicate and null values. Still, the primary key is a purely logical mechanism, and it doesn’t allow duplicate or null values in tables.

Q7. Define partitioned primary index and its advantages?

Answer:
A partitioned primary index is also referred to as PPI. PPI is called an indexing mechanism, which helps in improving the performance of the queries. PPI is being defined within the table, and rows are mainly sorted according to their partition number. It means records are arranged with a row hash. There are several advantages of PPI that are:

It helps in deleting the old data and adding the new data.
We can access the large table in less time compared to normal.
It helps in avoiding the additional maintenance for input and output.
While executing queries, only the necessary partition has been accessed rather than a full table.

Q8. Explain the purpose of the UPSERT command?

Answer:
This is the most asked Teradata Interview Questions in an interview. UPSERT command is used to perform the tasks Update Else Insert nature, and it is one of the features that are only available for Teradata.

Q9. Explain the difference between fast load and multi-load?

Answer:
A fast load is used to load a large amount of data to an empty table quickly to use multiple sessions. Multi-load is mainly used for non-empty tables, and it can be used with only 5 tables. Multi-load is mainly used to maintain the activities of high volume tables and views.

Q10. What does skewness mean and use of a Nullif function in Teradata?

Answer:
Skewness is referred to as the unequal distribution of data on AMPs, and the percentage of skewness is called a skew factor. Nullif function is used to compare the two arguments; if the two arguments matched, it will return null else, it returns the first argument.