Teradata Random 5 — Questions and Answers
Question 1: Which Teradata feature allows partitioning a table by a range of column values to improve partition elimination?
- Secondary Index
- Partitioned Primary Index (PPI) (Correct answer)
- Join Index
- Hash Index
Correct answer: Partitioned Primary Index (PPI)
A Partitioned Primary Index (PPI) divides table rows into partitions based on column value ranges, allowing the optimizer to skip irrelevant partitions during scans.
Question 2: In Teradata SQL, what does the QUALIFY clause do?
- Filters rows before aggregation
- Filters rows based on the result of an ordered analytical (window) function (Correct answer)
- Replaces a HAVING clause on grouped results
- Eliminates duplicate rows from a result set
Correct answer: Filters rows based on the result of an ordered analytical (window) function
QUALIFY filters the output of ordered analytical functions (similar to HAVING for aggregates), allowing conditions on window function results without a subquery.
Question 3: What is the effect of specifying CASESPECIFIC in a Teradata column definition?
- Forces uppercase storage of all values
- Makes string comparisons case-sensitive for that column (Correct answer)
- Enables collation-based sorting
- Converts all comparisons to Unicode
Correct answer: Makes string comparisons case-sensitive for that column
CASESPECIFIC makes character comparisons on that column case-sensitive, so 'ABC' and 'abc' are treated as different values.
Question 4: Which Teradata concept describes the maximum amount of disk space allocated to a user or database?
- Spool Space
- Temp Space
- Perm Space (Correct answer)
- Fallback Space
Correct answer: Perm Space
Perm Space is the maximum permanent disk storage quota allocated to a user or database for storing tables and their data.
Question 5: In Teradata, what is a Join Index used for?
- To enforce referential integrity between two tables
- To pre-join and aggregate data from one or more tables to accelerate query performance (Correct answer)
- To create a unique secondary index on a join column
- To store the result of a MERGE statement
Correct answer: To pre-join and aggregate data from one or more tables to accelerate query performance
A Join Index stores precomputed joins or aggregations of one or more tables, allowing the optimizer to satisfy certain queries from the index rather than the base tables.
Question 6: Which Teradata isolation level prevents dirty reads but still allows non-repeatable reads?
- Serializable
- Read Uncommitted
- Read Committed (Correct answer)
- Repeatable Read
Correct answer: Read Committed
Read Committed isolation prevents reading uncommitted (dirty) data but does not prevent another transaction from modifying a row between two reads in the same transaction.
Question 7: What Teradata administrative command releases all locks held by a specific session?
- ABORT SESSION (Correct answer)
- RELEASE LOCKS
- FLUSH SESSION
- KILL SESSION
Correct answer: ABORT SESSION
The ABORT SESSION command terminates the specified session and rolls back any in-progress transactions, releasing all associated locks.
Teradata Random 5
Which Teradata feature allows partitioning a table by a range of column values to improve partition elimination?