What is the most important thing to remember when designing a natural key?

1 Why use natural keys?

Natural keys have several advantages over artificial or surrogate keys, which are usually generated by the database system or the ETL process. Natural keys can improve data quality, integrity, and consistency, by ensuring that each row represents a distinct entity or event. Natural keys can also simplify data integration, analysis, and reporting, by making it easier to join tables across different sources and levels of granularity. Natural keys can also enhance data security and governance, by enabling access control and auditing based on business rules and logic.

2 How to choose natural keys?

Choosing natural keys is not always straightforward, and requires a good understanding of the business domain, the data sources, and the data warehouse requirements. The most important thing to remember when designing a natural key is to make sure that it is stable, unique, and meaningful. Stable means that the natural key does not change over time, or at least changes very rarely. Unique means that the natural key does not have any duplicates or conflicts within or across tables. Meaningful means that the natural key conveys some information about the row, and is not just a random or arbitrary value.

3 What to avoid when designing natural keys?

There are some common mistakes and challenges that you should avoid when designing natural keys. One of them is using too many or too few columns as natural keys. Too many columns can make the natural key too complex, cumbersome, and inefficient, while too few columns can make the natural key too vague, ambiguous, or inconsistent. Another mistake is using columns that are prone to errors, changes, or variations, such as names, addresses, phone numbers, or emails. These columns can compromise the stability and uniqueness of the natural key, and cause data quality issues. A third mistake is using columns that are irrelevant, redundant, or misleading, such as codes, flags, or indicators. These columns can reduce the meaning and value of the natural key, and confuse the users and analysts.

5 How to prepare for natural key questions?

Natural key questions are very common in data warehousing interviews, as they demonstrate your knowledge, skills, and experience in data modeling and design. To prepare for natural key questions, you should review the concepts and principles of natural keys, and practice with some examples and scenarios. You should also be able to explain the benefits and challenges of natural keys, and how to overcome them. You should also be ready to compare and contrast natural keys with other types of keys, such as surrogate keys, composite keys, or foreign keys.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?