Should You Use an Email Address as a Primary Key in Your Database?

Concerns about Using Email Address as Primary Key

In designing a database schema, the choice of primary key is crucial for ensuring efficient data retrieval and management. While some may consider using an email address as the primary key, concerns arise regarding its drawbacks compared to auto-incrementing numbers.

Speed Considerations

As mentioned by the questioner's colleague, string comparison for email addresses in SQL databases can be slower than integer comparisons for auto-incrementing numbers. Integer comparisons are inherently faster due to their fixed length and deterministic nature. However, this performance difference is generally not significant for simple queries that retrieve records based on the email address.

Data Redundancy

If the email address is used as the primary key, database tables that store user-related information will likely contain the email address as a foreign key. This leads to data redundancy, increasing storage space requirements and potentially compromising data integrity.

Assessment

In the context of PostgreSQL, which supports both integer and string primary keys, the decision of whether to use the email address as the primary key should be based on the specific requirements of the application. If performance is a critical factor and complex queries with multiple joins are likely to be executed, using an auto-incrementing integer as the primary key may be more appropriate.

On the other hand, if speed considerations are not paramount and data redundancy is not a significant concern, using the email address as the primary key can be acceptable, particularly in cases where it provides greater clarity and ease of understanding for data manipulation tasks.

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