Should You Use Email Addresses as Primary Keys Instead of Auto-Incrementing Numbers?

Is Email Address a Viable Primary Key Alternative to Auto-Incrementing Numbers?

When determining the primary key for a database table, email addresses come into consideration as a potential option, especially in web applications where user uniqueness is critical. However, concerns arise regarding the performance implications of using strings for primary keys compared to integer auto-incrementing fields.

Performance Concerns with Email Primary Keys

It's true that string comparisons are inherently slower than integer comparisons. This difference becomes noticeable during complex queries involving multiple joins or when frequently retrieving data using the email address. The repeated string comparison operations can add up to significant overheads.

Data Integrity Considerations

While email addresses provide a unique way to identify users, they come with data integrity challenges. Specifically, the multiple storage of email addresses as foreign keys across multiple tables can be problematic. This leads to potential inconsistencies and database bloat.

PostgreSQL's Considerations

For PostgreSQL specifically, the use of email addresses as primary keys poses additional challenges. PostgreSQL uses B-Tree indexes to optimize queries, but these indexes don't perform as efficiently with string primary keys. This can lead to slower query performance compared to using integer primary keys.

Recommendation

Based on these considerations, it's generally advisable to use auto-incrementing integers as primary keys whenever possible. While email addresses may be a convenient choice for user identification, their performance implications and data integrity concerns make them a less optimal primary key candidate compared to numerical values.

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