Practice Selection (sigma) Operation (filtering Rows) (8.4.1) - Query Processing and Optimization
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Selection (sigma) Operation (Filtering Rows)

Practice - Selection (sigma) Operation (Filtering Rows)

Learning

Practice Questions

Test your understanding with targeted questions

Question 1 Easy

What is the purpose of the selection operation in databases?

💡 Hint: Think of filtering data based on certain criteria.

Question 2 Easy

What happens during a Full Table Scan?

💡 Hint: Consider how you would check each item in a list.

4 more questions available

Interactive Quizzes

Quick quizzes to reinforce your learning

Question 1

What does the selection operation in relational algebra do?

A) Filters rows from a relation based on a condition
B) Joins two relations
C) Projects specific columns from a relation

💡 Hint: Recall the meaning of sigma in this context.

Question 2

True or False: A Full Table Scan is more efficient when most rows will satisfy the selection condition.

True
False

💡 Hint: Consider the scenario of searching for a common item.

1 more question available

Challenge Problems

Push your limits with advanced challenges

Challenge 1 Hard

You have a database table of products with 100,000 entries. Describe the steps and considerations for optimizing a selection query on a rarely updated column with no index available.

💡 Hint: Focus on the size and content of your data.

Challenge 2 Hard

A query returns 90% of a dataset. Discuss how this selectivity impacts selection strategy and resource utilization.

💡 Hint: Reflect on how selective filters enhance performance.

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Reference links

Supplementary resources to enhance your learning experience.