Lookup Tables: IDs or Values – Which Approach Should You Choose for Optimal Database Design?

Decision: Lookup Table IDs vs. Lookup Table Values Direct Store

While storing data, deciding between using foreign keys to lookup tables or incorporating lookup table values directly into the requesting tables is a common dilemma. This article explores the considerations and provides guidance for making an informed decision based on specific circumstances.

Considerations:

• Mass Updates: Using lookup table values directly requires mass updates if data changes in the lookup table. This can be a significant overhead for heavily referenced columns.
• Foreign Key Joins: Using foreign keys introduces joins during queries, potentially impacting performance when multiple lookup tables are referenced.
• Data Integrity: The second method requires matching data when reloading, ensuring that values are present in the existing lookup lists.
• Data Type: The lookup table primary key data type should be considered to minimize index overhead and foreign key size impact.

Best Practice:

The optimal approach depends on the specific scenario. However, a recommended solution involves using a lookup table with a VARCHAR primary key and a foreign key in the main data table with cascading updates. This provides:

• Querying color names without joining
• Data integrity through constrained color names
• Efficient lookup table management
• Automated cascading updates when color changes are made

Additional Points to Consider:

It's important to note that using surrogate keys (IDs) does not impact normalization.

When choosing a lookup table primary key data type, size should be factored in, as secondary indexes store primary key values.

Ultimately, the best decision should be made on a case-by-case basis, weighing the trade-offs and considering the specific requirements and limitations of the system.

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