SQL Query Optimization and Indexing

What is the primary key column in the 'person' table?

• first_name

• last_name

• person_id

• birthday

Why is it important to measure the execution time of SQL queries?

• To verify data accuracy

• To ensure the database is secure

• To optimize query performance

• To check for syntax errors

What was the average time taken to scan the entire 'person' table without indexes?

• 4,480 milliseconds

• 4,274 milliseconds

• 4,261 milliseconds

• 3,562 milliseconds

How does an index in a database function similarly to an index in a book?

• It allows quick access to specific data

• It provides a list of all data entries

• It stores data in alphabetical order

• It summarizes the contents of the database

What was the impact of creating an index on the 'first_name' column?

• It had no effect on any queries

• It improved query speed for first name searches

• It slowed down all queries

• It improved query speed for last name searches

Why did the query for 'Smith' not improve after creating a 'first_name' index?

• The database was too large

• The index was not created correctly

• The 'Smith' query was already optimized

• The index was not on the 'last_name' column

What is a query plan in the context of databases?

• A backup of the database

• A summary of query results

• A strategy for executing a query

• A list of all tables in the database

What is the advantage of a multi-column index?

• It simplifies database design

• It eliminates the need for primary keys

• It speeds up queries involving multiple columns

• It reduces storage requirements

How did the multi-column index affect the query for 'John Williams'?

• It caused an error in the query

• It slowed down the query

• It had no effect on the query

• It significantly sped up the query

What is a potential downside of using indexes in a database?

• They make the database less secure

• They require frequent updates to the database schema

• They increase storage requirements

• They slow down all queries