Optimize Joins by Indexing Foreign Key Columns

Creating an Index on a Foreign Key Column in PostgreSQL

Write a PostgreSQL query to create an index on a foreign key column to optimize join performance.

Solution:

-- Specify the action to create an index.
CREATE INDEX idx_employees_department_id 
-- Define the target table and column for the index.
ON Employees(department_id);

Explanation:

• Purpose of the Query:
• To enhance join performance between the Employees table and the Departments table using the foreign key.
• Key Components:
• CREATE INDEX idx_employees_department_id : Names the new index.
• ON Employees(department_id) : Specifies the column that references the foreign table.

Notes:

• Indexing foreign keys improves the speed of join operations and lookups.
• It is a common practice to index columns that are used in relational joins.

For more Practice: Solve these Related Problems:

• Write a PostgreSQL query to create an index on the "department_id" foreign key column in the "Employees" table.
• Write a PostgreSQL query to create an index on the "customer_id" foreign key column in the "Orders" table.
• Write a PostgreSQL query to create an index on the "category_id" foreign key column in the "Products" table.
• Write a PostgreSQL query to create an index on the "user_id" foreign key column in the "Comments" table.

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Previous PostgreSQL Exercise: Creating a Case-Insensitive Index.