Data Science



Crack Teradata Interview Questions Like a Pro

Teradata is a widely utilized relational database management system (RDBMS) that is recognized for its special capabilities of being sustained data and transactions, absolutely stellar in parallelism, comprehensive security features, effectiveness, strong and vibrant structure, greater convenience for scalability, capacity to support SQL querying, etc. The essential characteristics consist of a storage architecture, access module processors (also known as AMPs), a parsing engine, and a message parsing layer that corresponds to it.

Teradata Tools and Utilities (TTU) is a set of Teradata Client tools for server operating systems like GNU/Linux. It allows users to connect to Teradata database instances and contains load and unload utilities, connection drivers, and other similar components.

The following constituent parts make up the Teradata database system:

  • Call level interface (CLI)
  • The WinCLI programming interface and open database connection (ODBC)
  • Teradata Director Program (TDP)
  • Micro Transistor-driven-processing System

Now, let’s have a look at the top questions that can be asked in interviews about Teradata. 

Teradata Interview Questions with Answers

  • What is Teradata?

Teradata Corporation is the company that offers the relational database management system known as Teradata. Regularly, you have utilized it for projects involving the storing of large amounts of data for a variety of client applications.

Teradata was designed with parallelism as its foundation, which equally distributes work across several processors and executes activities in parallel. In addition to this, it operates like a server and has the capability of being scaled to meet varying demands in terms of data processing. This is an open system, may operate on a single node or several nodes simultaneously, and is compatible with the American National Standards Institute. 

1. What are the sorts of tables that Teradata can handle and how do you use them?

Teradata allows for the creation of four distinct kinds of tables in its databases. The following are the items in question:

Permanent table – These are used to store data in the system in a way that is intended to be there indefinitely. The permanent table is the kind of table that is used as the default.

Tables that only save data – These are volatile tables that are there for the duration of the current user session. These tables, along with their contents, will be deleted when the user session comes to an end. When complicated computations or data transmissions are taking place, it is essential to have these tables available to hold interim data.

Global temporary table – The global temporary table is being used to store the globally utilized values throughout the program and its validity is limited to the currently active user session alone. The table, along with its contents, will be deleted when the user session comes to an end.

Derived table – They have always had the shortest lifespan up to the point at which a query is executed. When a query is being executed, these tables are used to temporarily store interim results.

  • How can we generate a sequence in the Teradata database?

We can generate sequences in Teradata by making use of the identity column.

  • What exactly does it imply when someone refers to Teradata as “caching”?

Caching is seen as an additional benefit associated with the use of Teradata since the database is mainly designed to operate with a source that maintains the same order over time, that is, one that is not subject to frequent modification. The cache is often shared across many programs as a matter of course.

  • Describe how the Teradata system is structured?

There are three separate parts that make up the Teradata architecture.

Parsing Engine

The user submits a query, which is then received by Parsing Engine, which then does an analysis of the query and creates an execution plan.

BYNET

BYNET obtains the execution plan from Parsing Engine and then sends it to the relevant AMP.

AMP 

AMP is in charge of storing as well as retrieving entries from the database. It saves the information inside the virtual disc that is linked to it. In addition to all this, AMP is accountable for the administration of locks and spaces, in addition to the collection and sorting of data.

  • What exactly is the multi-insert being referred to here?

The process of adding new data entries to a table by executing many insert statements at once is referred to as multi-insert. To do this, in the following line, rather than ending the first statement with a semicolon, we will position the semicolon at the front of the keyword INSERT. This will give us the desired result.

  • Insert into Cname “select * from customer”;
  • Insert into amount “select * from customer”;
  • What exactly is the main index in Teradata and how does it work?

Within a Teradata system, the main index is the method that identifies the location of the data storage locations. When working with Teradata, it is essential for each table to have the main index configured. If the main index for the table is not given, Teradata will choose one for it automatically. This is because the primary index enables users to retrieve data more quickly. Primary indexes may be divided into two different categories: the unique primary index and the non-unique primary index.

  • Define AMP in Teradata?

 Access Module Processor, sometimes known as AMP, is an essential component of the Teradata architecture that is responsible for storing data on drives.

A section of a database or a table may be managed with the assistance of AMP. Through the production of a result set, it guarantees that all of the tasks will be finished. It manages the space and locks, which is one of the many ways it offers its wide help.

  • Could you please explain what you mean by the term Teradata Intelliflex?

The Teradata Intelliflex platform was developed with scalable enterprise analytics in mind from the very beginning. It utilizes innovative self-service software controls with MPP architecture for the scalability of computing data and power capacity independently.

  • Explain why multi-load prefers to support NUSI over USI and provide a justification for this decision?

It just so happens that the data row in NUSI and the index subtable row are both located on the very same AMP in the same manner. As a result, each AMP is run in a way that is independent of the other and in parallel.

  • Which one is more advantageous, IN or BETWEEN?

If we need to search a range of outcomes, we should always make use of the BETWEEN operator rather than a list of values included inside the IN clause.

  • After the execution, how does one restart the MLOAD Teradata Server?

After the data has already been carried out following the execution of the MLOAD script, the server is restarted. The procedure is essentially carried out from the most recent known checkpoint.

  • What exactly does the BTEQ utility do in Teradata?

The BTEQ utility is perhaps the most powerful tool that can be found in Teradata. It is handy for batch processing as well as interactive mode. It is also possible to utilize it to execute any DDL statement or DML statement, as well as to create macros and stored procedures. Importing data into Teradata tables from a flat file is yet another significant use of the BTEQ tool. In addition to this, it is practical for extracting data from a table into files or reports.

  • What steps need to be taken to restart the MLOAD Client System once it has failed?

In the event that a Teradata MultiLoad job was terminated before or during the application process, you need to resume the job exactly as it was, without making major changes to the script. The point at which Teradata MultiLoad stops processing is determined by the entries in the restart log table. The program then starts processing from that point. 

In the event when  a Teradata MultiLoad job is terminated or the client system fails even during the application stage, the problem that caused the failure must be fixed before the job can be re-started.

  • What is the purpose of indexes?

The performance of accessing tables may be improved by the SQL query optimizer via the use of a technique known as index. Notably, indexes improve data access by giving a more or less direct route to stored data as well as reducing the requirement to execute complete table scans in order to identify the limited number of rows that a user generally wants to get or edit. Indexes are a key component of many database management systems.

  • Explain what the distinctions are between primary index and primary key?

The primary index is the method that pinpoints the location of the data that is included inside the Teradata system. In Teradata, each table has a primary index associated with it. Teradata will automatically assign a primary index when there is no primary index that has been defined.

The primary key is a value that is one of a kind and is used to represent a row in the table. The primary index must always be included, although the primary key may be skipped if desired. The main key does not permit duplicates or values that are null, whilst the primary index does permit both of these things. While the main key relies on a logical method, the primary index makes use of a physical process.

  • Explain Vproc in Teradata?

Vproc, also known as virtual processor, is a simulated processor that may be found in a processing software system or a software version of a dedicated physical processor in the Teradata database system. Each Vproc operates independently of the other virtual processor while using a fraction of the resources provided by the physical processor.

  • In Teradata, what exactly are database privileges?

An authorization to access or alter an item or piece of data stored in a database is known as a database privilege. When working with Teradata database, you will almost always need to have the appropriate rights to complete a task. Administrators of a Teradata database make use of privileges to regulate the sorts of actions and activities that users are permitted to engage in, as well as the access users have to database objects and data.

  • Explain surrogate keys in Teradata? 

In Teradata, a surrogate key is a key that is used to transfer the natural keys that are found in source systems to a different key, which is often an integer number. The majority of the time, one or maybe more natural key fields are mapped to a surrogate key that is worthy of an integer. It is not uncommon for a series of consecutive numbers to be produced.

  • Could you please explain Teradata parallel data extension to me?

Parallel data extension or PDE is a layer of software that acts as an interface layer between the Teradata database and the operating system. PDE provides support for parallelism by using the system’s nodes. It contributes to the speed of the Teradata database as well as its linear scalability. At the PDE level, there are a lot of different tools like diagnostic and troubleshooting functions.

The PDE tools included with Teradata database are a collection of several PDE utilities. They are not included in the utility section since PDE tools have their online documentation, which may be accessed from the system console by using the “pdehelp” as well as “man” commands, respectively.

Final Thoughts

Well, these are the top questions that you must prepare for your interview when going for a job involving Teradata. Along with these, you must also practice the execution of train commands and work on your verbal skills to make yourself clear when answering the questions. We hope that these questions, along with the given answers, will help you in securing a great job in the industry. 

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