What is normalization?
- Normalization is a series of steps that convert a flat or poorly structured table into multiple related tables, following standard normal forms (1NF to 3NF and beyond).
Goals of normalization
| Goal | Why? |
|---|---|
| Eliminate redundancy | No duplicate data in multiple places |
| Ensure data integrity | One version of the truth |
| Improve flexibility | Easier to update and scale |
| Better queries | Relational design improves join logic |
The normalization in 3 main forms
1NF (first normalization form)
Ensure atomic values (no lists or arrays in one column)
Each record has a unique identifier (primary key)
2NF (second normalizaiton form)
Be in 1NF
Move partial dependencies to other tables
3NF (third normalization form)
Be in 2NF
Remove transitive dependencies (non-key columns depending on other non-key columns)
Process
Identify repeating groups or redundant data
Create separate tables for each entity (customer, product, department, etc.)
Assign primary keys to each new table
Replace repeated fields with foreign keys
Update your queries to use JOINs
When Not to Normalize Fully
Normalization is great for integrity, but over-normalizing can hurt performance, especially in read-heavy systems like reporting dashboards.
In some cases, denormalized tables are used for:
Fast reporting (data warehouses)
Aggregated tables
NoSQL systems
Final Summary
| Why Normalize? | When to Normalize |
|---|---|
| Reduce Redundancy | During initial database design |
| Improve data integrety | When refactoring legacy systems |
| Simplify maintenance | During optimzation or migration |
| Avoid anomalies | After discovering data issues |
| Avoid anomalies | In preparation for scalability |