Database design choice: Using string primary keys vs integer identity columns

Data and Databases
1

I’m working on a database design and need some advice on primary key strategy.

I have a database where the main identifier is a string value. I’m torn between two approaches and wondering which one performs better.

Option 1 - String as primary key:

Employees
======================
employee_name    varchar(10)   
birth_date       DateTime    
salary          int  

Contact_Info
======================
employee_name    varchar(10)   
phone           varchar(15)

Option 2 - Integer identity with string as regular column:

Employees
======================
emp_id          int Identity   
employee_name    varchar(10)   
birth_date       DateTime  
salary          int  

Contact_Info
======================
emp_id          int   
phone           varchar(15)

There will be multiple related tables with one-to-many relationships. The first option seems easier to implement but I’m concerned about performance. The second option adds complexity but might be faster for joins and indexing.

Which approach would you recommend and what are the main reasons?

2

Honestly depends what you’re building, but i’d go with option 2. One thing nobody mentioned - varchar primary keys fragment like crazy since inserts aren’t sequential like auto-increment ids. Your clustered index gets messy and performance tanks. Plus debugging sucks when you’re staring at random strings in logs instead of clean numbers.

3

interesting dilemma! quick question though - are employee names actually unique in your system? what happens with two john smiths? also, how often do these string values change? if someone gets married and changes their name, you’d have to update foreign key references everywhere instead of just changing one record with an integer primary key. that sounds like a nightmare.

4

Go with Option 2, no question. String primary keys will kill your performance once your data grows. Integer comparisons blow string comparisons out of the water, plus integer indexes use way less memory and have better cache locality. I got burned on this exact thing - we started with natural string keys and had to migrate later when our joins crawled to a halt. The storage overhead from all those varchar foreign keys adds up fast when you’ve got multiple related tables. Trust me, the extra complexity is nothing compared to the performance nightmare and maintenance hell you’ll deal with using string primary keys at scale.