Maintaining Data Integrity: Why You Can't Reorder Columns in PostgreSQL (and What to Do Instead)

Why can't we reorder columns?

• Relational model: Unlike spreadsheets, relational databases access data by column names, not their position in the table. This ensures consistent data access regardless of the order columns appear in any specific query or user interface.
• Data integrity: Changing the physical order might require modifying stored data, potentially leading to inconsistencies and errors, especially when accessing the table from different applications or tools.

Example:

Imagine a table users with columns id, name, and email. They can be accessed in any order:

SELECT email, name FROM users;
SELECT name, id FROM users;

Both queries will work correctly regardless of the physical column order.

Related Issues and Solutions:

While direct reordering isn't possible, here are alternative approaches:

• Views: Create a view that selects columns in your desired order. This acts as a virtual table with the preferred column sequence.

CREATE VIEW user_details AS
SELECT name, email, id FROM users;

SELECT * FROM user_details;  -- Shows columns in the order defined in the view

• Application logic: If your concern is presenting data in a specific order within your application, handle the ordering within your code using programming languages like Python or Java.