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.
What are BTEQ COMMAND?
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
ERROR OUT, EXPORT, HALT EXECUTION, IMPORT, INDIA DATA, OS, QUIET, Repeat, run, etc.
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.