Interview Questions On Teradata

What is Teradata?

Teradata is one of the popular Relational Database Management System. It is mainly suitable for building large scale data warehousing applications. Teradata achieves this by the concept of parallelism. It is developed by the company called Teradata.

Define Teradata RDBMS?

Teradata RDBMS is a complete relational database management system. The system is based on off-the-shelf Symmetric Multiprocessing (SMP) technology combined with a communication network connecting the SMP systems to form a Massively Parallel Processing (MMP) system.


BTEQ Command Classified in the below 4 types:

a)Session control commands

ABORT, EXTI, Halt EXECUTION, LOGON, LOGOFF, QUIT, Session, charset, session transaction, show versions, etc.

b)File formatting commands


c)Sequence control commands

Abort, error level, Exit, GO TO, quite, IF Then, Label, etc

d)Format control commands

Side titles, fold line, Footing, Heading, etc.

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Why is Aggregation expensive in a parallel DB ?

In order to aggregate records, they have to be on the same processing unit

This requires a redistribution of the records according to the “Group by” clause

Aggregation is more expensive than a Join, because more records have to be processed, normally, and a mathematic operation (sum, avg, min, max) is performed additionally

Each VAMP aggregates his local records first

Then the intermediate results are redistributed using Hash for the final aggregation

Each AMP performs a local count, then executes a share of the global count

Which Is Faster Fastload Or Multiload?


How Do You See A Ddl For An Existing Table?

By using show table command.

What Is Data Mart?

A data mart is a special purpose subset of enterprise data used by a particular department, function or application. Data marts may have both summary and details data, however, usually the data has been pre aggregated or transformed in some way to better handle the particular type of requests of a specific user community. Data marts are categorized as independent, logical and dependant data marts.