Teradata MCQ Flashcards

Which Teradata compression type stores repeated column values once in the table header rather than in each row block?

Answer: Multi-Value Compression (MVC)

Multi-Value Compression replaces frequently occurring column values with a small token stored in the row header, reducing row size.

In Teradata, what is the maximum number of Secondary Indexes allowed per table?

Answer: 64

Teradata allows up to 64 secondary indexes (USI + NUSI combined) to be defined on a single table.

Which function in Teradata returns the position of the first occurrence of a substring within a string?

Answer: POSITION() or INSTR()

POSITION(substring IN string) and its alias INSTR() both return the 1-based character position of the first match.

What does the Teradata 'NORMALIZE' clause do when applied to a table of time periods?

Answer: Merges overlapping or adjacent time periods into a single contiguous row

NORMALIZE collapses adjacent or overlapping PERIOD column rows with identical non-period attributes into a single merged row.

Which Teradata view provides real-time information about currently running queries and their AMPs usage?

Answer: DBC.SessionInfoV

DBC.SessionInfoV shows active sessions and their current SQL text, state, and resource usage in near-real time.

In Teradata, what distinguishes a Unique Secondary Index (USI) from a Non-Unique Secondary Index (NUSI)?

Answer: USI guarantees one row per index value and uses 2 AMPs; NUSI allows duplicates and involves all AMPs

A USI enforces uniqueness and accesses exactly 2 AMPs for a lookup; a NUSI allows duplicate values and typically scans all AMPs.

Which Teradata Parallel Transporter (TPT) operator is used to read data from a Teradata table and export it to a flat file?

Answer: Export operator

The TPT Export operator uses the FastExport protocol to read rows from Teradata and deliver them to downstream operators or files.