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Question 3 - DEA-C01 discussion

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A company's data engineer needs to optimize the performance of table SQL queries. The company stores data in an Amazon Redshift cluster. The data engineer cannot increase the size of the cluster because of budget constraints.

The company stores the data in multiple tables and loads the data by using the EVEN distribution style. Some tables are hundreds of gigabytes in size. Other tables are less than 10 MB in size.

Which solution will meet these requirements?

A.

Keep using the EVEN distribution style for all tables. Specify primary and foreign keys for all tables.

Answers
A.

Keep using the EVEN distribution style for all tables. Specify primary and foreign keys for all tables.

B.

Use the ALL distribution style for large tables. Specify primary and foreign keys for all tables.

Answers
B.

Use the ALL distribution style for large tables. Specify primary and foreign keys for all tables.

C.

Use the ALL distribution style for rarely updated small tables. Specify primary and foreign keys for all tables.

Answers
C.

Use the ALL distribution style for rarely updated small tables. Specify primary and foreign keys for all tables.

D.

Specify a combination of distribution, sort, and partition keys for all tables.

Answers
D.

Specify a combination of distribution, sort, and partition keys for all tables.

Suggested answer: D

Explanation:

This solution meets the requirements of optimizing the performance of table SQL queries without increasing the size of the cluster. By using the ALL distribution style for rarely updated small tables, you can ensure that the entire table is copied to every node in the cluster, which eliminates the need for data redistribution during joins. This can improve query performance significantly, especially for frequently joined dimension tables. However, using the ALL distribution style also increases the storage space and the load time, so it is only suitable for small tables that are not updated frequently or extensively. By specifying primary and foreign keys for all tables, you can help the query optimizer to generate better query plans and avoid unnecessary scans or joins. You can also use the AUTO distribution style to let Amazon Redshift choose the optimal distribution style based on the table size and the query patterns.Reference:

Choose the best distribution style

Distribution styles

Working with data distribution styles

asked 29/10/2024
Zdenek Kugler
32 questions
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