Teradata Architecture Flashcards

What is a Primary Index in Teradata and why is it important?

Answer: It determines data distribution across AMPs and is critical for query performance

The Primary Index determines how rows are distributed across AMPs; a well-chosen PI ensures even distribution and efficient row retrieval.

What is the difference between a Unique Primary Index (UPI) and a Non-Unique Primary Index (NUPI)?

Answer: UPI guarantees one row per AMP bucket; NUPI allows multiple rows to hash to the same AMP

A UPI ensures no two rows share the same hash value, guaranteeing a single row per hash bucket, while NUPI allows duplicates on the same AMP.

In Teradata, what is a Secondary Index used for?

Answer: Provides an alternate access path to data without redistributing rows

A Secondary Index creates an alternate access path so queries not using the PI can still access rows efficiently without a full-table scan.

What is the purpose of Fallback in Teradata?

Answer: Stores a second copy of each row on a different AMP for fault tolerance

Fallback protection keeps a duplicate copy of every row on a different AMP, ensuring data availability if one AMP fails.

What is a node in Teradata's hardware architecture?

Answer: A physical server containing CPUs, memory, and disk that hosts multiple Vprocs

A node is a physical server with its own CPUs, memory, and I/O that hosts multiple Parsing Engines and AMPs (Vprocs).

What does the Teradata Data Dictionary contain?

Answer: Metadata about all database objects such as tables, views, users, and indexes

The Data Dictionary stores system-level metadata including definitions of tables, views, indexes, stored procedures, and user access rights.