Data Warehousing on AWS Training Data Warehousing on AWS: Data Modeling 3

Question 1

Which Redshift encoding type is best suited for a low-cardinality string column such as a status field with values like 'ACTIVE', 'INACTIVE', 'PENDING'?

Accepted Answer

BYTEDICT

Answer

BYTEDICT encoding creates a dictionary of distinct values and stores references, making it highly efficient for low-cardinality string columns.

Question 2

What does the Redshift VACUUM SORT ONLY command specifically address?

Accepted Answer

Re-sorts unsorted rows added after the initial load without reclaiming space

Answer

VACUUM SORT ONLY re-sorts the unsorted region of a table without reclaiming space from deleted rows, improving query performance.

Question 3

A retail data warehouse fact table stores daily sales. An analyst frequently runs queries filtering by both product_category and sale_date. What interleaved sort key design should be used?

Accepted Answer

INTERLEAVED SORTKEY (sale_date, product_category)

Answer

INTERLEAVED sort keys give equal weight to all columns, making INTERLEAVED SORTKEY (sale_date, product_category) efficient when filters alternate between columns.

Question 4

In AWS Glue Data Catalog, what role does it play in a data lake architecture on AWS?

Accepted Answer

It provides a centralized metadata repository for tables in S3 and other sources

Answer

The AWS Glue Data Catalog is a managed metadata store that maintains table definitions, schemas, and partitions for use by Athena, Redshift Spectrum, and EMR.

Question 5

Which type of Redshift table is automatically refreshed and can be used to pre-aggregate common query patterns to improve performance?

Accepted Answer

Materialized view

Answer

Materialized views in Redshift store pre-computed results and can be configured to auto-refresh, accelerating repetitive aggregation queries.

Data Warehousing on AWS Training Practice Test

Data Warehousing on AWS Training Practice Test

Data Warehousing on AWS Training Data Warehousing on AWS: Data Modeling 3