Teradata is one of the latest relational database management systems for building data warehouse applications. Utilization of Teradata to perform the functionalities related to databases is increasing exponentially. Business organizations and companies are looking for individuals who have basic knowledge of Teradata. This article covers Teradata Interview questions that will help you in cracking the interview easily. This guide also includes the frequently asked questions on Teradata that will enhance the knowledge of Teradata. Teradata interview questions will ultimately help you in attaining the best job in the industry. Let us have a quick review of the top 30 interview questions asked in the interview.
Ans: Teradata is a Relational Database management system that allows the users to perform data functionalities. Teradata is for the creation and management of the databases, datamart, data warehouses, etc. Teradata is well known for its parallel processing model that concisely allows the management of data. Many organizations use Teradata as it is faster and flexible than any other database management system. Some of the key characteristics of Teradata are:
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Ans: Both Teradata and Oracle are Relational database management systems that allow the management of databases. Oracle uses the Object-Relational Database management system while Teradata uses Relational database management systems.
Oracle uses an architecture that follows the term "Shared Everything ", whereas Teradata uses non Shared architecture. Teradata uses non-conditional parallelism whereas Oracle uses conditional parallelism. Teradata is termed as linearly scalable.
Ans: The newly developed features in Teradata are listed below:
Ans: The most commonly used BTEQ scripts are:
Ans: Teradata includes a large number of different destinations, while RDBMS does not include various destinations. Source operation is allowed in Teradata while RDBMS does not permit. Components can be reused in Teradata for any number of times while in RDBMS, it is limited. Debugging is easy in Teradata while it is complex in RDBMS.
Ans: The duplicates in the table can be found by grouping the fields and select id, count (*) from table group by id having count (*) > 1.
The version of Teradata is determined by using the command ".SHOW VERSION".
Ans: Views refer to the database objects built using queries on multiple tables or a single table. Data for the view is a dynamic process at the execution time.
Ans: Teradata comprises an added advantage called Caching, which specifically works with the source represented in the same order. In simpler terms, frequent changes do not take place. In some scenarios, cache sharing is allowed amongst different applications.
Ans: There are two different methods to restart the system. The user can start running the old files without dropping the table. Another approach is to run a new file that generates scripts and removes all the conflicts from the tables.
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PDE: PDE(Parallel Data Extension) is an interface layer of software that allows the database to perform the functionalities by operating in a parallel milieu. The parallel data extension layer is present above the operating system.
TPD: TPD( Trusted Parallel Database) works under Parallel Data extension. As TPD works under PDE, Teradata is also known as a Trusted parallel or Pure parallel database.
PPI: PPI (Partition Primary Index) used for category based or range-based data storage operations. Concerning the Range based queries, a Full table scan utilization is not required as it moves to the consequent partition by skipping the other partitions.
Ans: There are four different forms of locks represented under Teradata. They are:
Ans: A dispatcher refers to the collection of the requests and stores them in the form of a queue. Dispatcher utilizes the same queue to provide multiple sets of responses. A dispatcher is used to perform various tasks at a time by storing numerous requests in a defined manner.
Related Article: OLAP functions in Teradata
Ans: Effective communication should be established while handling tasks related to data management between the applications and the PEs. To ensure and develop an interface of communication, Channel driver software is used. It serves as a direct link between applications and PEs.It also enables the sharing of data efficiently.
There is a minute difference between Channel driver and Gateway. Gateways enable communication only for network clients or clients that are attached to the network.
Ans: AMP (Access Module Processor) is an integral part of Teradata architecture that stores the data on the disks.AMP is used to manage a part of a database or a table. It ensures that all the tasks are accomplished by generating a result set. It provides its extensive support by performing space and lock management.
Ans: Teradata has a wide variety of components that provides the desired outputs within a short period. Some of the important elements of Teradata are listed below:
Ans: Teradata comprises a unique command called "Update else Insert" (USERT), which is only applicable in Teradata.
Related Article: Teradata SQL Assistant
Ans: Fastload loads a large amount of data on an empty table by using multiple sessions. Multiload is used for loading and performing functionalities on high volume tables and views. It is capable of working with non-empty tables too. Multiload allows a maximum of 5 tables. Among Fastload and Multiload, Fast load is faster.
Ans: Teradata comprises a unique feature called FALLBACK, which allows it to handle AMP failures. It is capable of protecting the data by storing a copy of each row, if VPROC failure occurs.
FALLBACK is transparent, automatic, default-enabled when Teradata is deployed in a system. It is available at both the table level and the database level.
Ans: There are various types of Joins available in Teradata. They are listed below:
Inner Join: Joins the records from multiple tables and provides a result of the values in both the tables.
Left Outer Join: Returns all the records in the left table and matching records from the right table.
Right Outer Join: Provides a result that returns all the records in the right table and matching records from the left table.
Full Outer Join: Full Outer join is a combination of left outer join and right outer join. It returns all the values that are matching and non-matching from both the tables.
Self-Join: Self Join compares the column values with the other values in the same column of the table.
Cross Join: Cross Join joins every row of the right table to every row of the left table.
Cartesian Product Join: It is similar to cross join.
Ans: Star schema in Teradata represents the blueprint of multi-dimensional data. It contains at least one measurement and reality tables. The pattern is represented in the form of a star as the entity-relationship between the measurements and reality tables will form a star. A table is associated with many measurements. Star pattern possesses advantages like execution increment, information comprehension.
Ans: A clique is a group or assortment of nodes that are shared among common disk drives. To avoid failure of nodes, the clique is used in Teradata. Each multi-node at least has one clique.
Ans: VPROC refers to a Virtual Processor, an instance of the processor software on the Teradata platform. Each VPROC uses a portion of the processor's physical resource and runs independently.
Ans: An execution is performed in UNIX represented in the below format.
$Sh > BTEQ < [Script path] TEE [Logfile Path]
$Sh > BTEQ < [Script Path] > [Logfile Path]
Ans: Primary Index is the technique that specifies the location of data that exists in the Teradata. Every table consists of a Primary index in Teradata. If there is no primary index specified, Teradata will assign a Primary index itself.
The primary key is the unique value that represents a row in the table. Primary Index is mandatory while the Primary key is optional. The primary key does not allow duplicates or null values, whereas the Primary index allows the same. The primary key comprises a logical mechanism, while the Primary Index utilizes a physical mechanism.
Ans: Teradata Gateway is used to establish communication between the parsing engine and the network client-based applications. Teradata Gateway is similar to Channel drive that drives an interface between network clients and parsing engine. One Gateway is related to one node.
Related Article: CSUM in Teradata
Ans: Generation of sequence can be accomplished in Teradata using a sub-feature called CSUM. All the components need not be applied at the same time. Instead, they can be used based on the task and requirements.
Ans: The difference between UNION ALL and UNION is simple. UNION ALL represents the result set values including the duplicates while UNION represents the result set values by ignoring the duplicates
Ans: Set operators are used to combining and returning the results from multiple select statements. Set operators are different from Join operators as Join operators work on combining the columns in various tables. Set operators are specifically used to combine different rows.
There are four different operators defined in Teradata. They are listed below:
Ans: There are four different types of tables supported by Teradata. They are listed below:
Permanent table: It is a default table used to store the data permanently in a system.
Volatile table: In this type of data table, the data will be stored only during the session. Once the session ends, the table drops along with the data.
Global Temporary table: Global Temporary data also stores the data during a particular session like the volatile table. However, the global temporary table only stores the global values used during the session.
Derived table: Derived tables have the shortest lifetime as they hold the intermediate result values represented during the execution of a query.
Ans: A journal represents the capture or a record of an activity performed. The system, on its own, performs Journaling. The different types of Journals are listed below:
Ans: A database privilege refers to the permissions given to an individual or developer to access and perform any function. To make any changes in the Teradata database, database privileges are required. The different types of privileges necessary to complete any functionality on Teradata database are: