Enhance Query Speed Using Covering Indexes

Using Covering Indexes for Faster Queries

Write a SQL query to create a covering index for a query.

Solution:

-- Create a covering index for a query that retrieves EmployeeID and Name.
CREATE INDEX IX_Employees_Covering
ON Employees (EmployeeID)
INCLUDE (Name);

Explanation:

• Purpose of the Query :
• The goal is to create a covering index that includes all columns required by a query.
• Key Components :
• CREATE INDEX: Creates an index on the EmployeeID column.
• INCLUDE (Name): Adds the Name column to the index for faster retrieval.
• Why Use Covering Indexes? :
• Covering indexes eliminate the need for additional lookups, improving query performance.
• They are ideal for queries with specific filtering and projection requirements.
• Real-World Application :
• In e-commerce systems, covering indexes speed up product search queries.

Notes:

• Covering indexes consume more storage space than regular indexes.
• Use them for frequently executed queries with predictable patterns.
• Important Considerations:
• Balance the trade-off between storage and performance.

For more Practice: Solve these Related Problems:

• Write a SQL query to create a covering index for a query that retrieves product ID, name, and price.
• Write a SQL query to create a covering index for a query that fetches customer ID, name, and email.
• Write a SQL query to create a covering index for a query that displays order ID, customer ID, and order date.
• Write a SQL query to create a covering index for a query that retrieves employee ID, name, and department.

Go to:

• Optimize SQL Performance with Query Tuning Exercises Home ↩
• SQL Exercises Home ↩

PREV : Avoiding SELECT * for Better Performance.
NEXT : Optimizing Queries with WHERE Clauses.

Have another way to solve this solution? Contribute your code (and comments) through Disqus.