MySQL ENUM Performance Considerations

Using ENUM can impact performance in certain scenarios. While it offers benefits in enforcing data integrity, there are potential drawbacks to consider.

Performance Penalty for Specific Operations

When dealing with a field that has only a limited number of possible values (5-10), ENUM may not offer a performance advantage. In fact, there can be a significant negative impact on certain operations, such as:

• Querying Permitted Values: Fetching the list of permitted values from the ENUM column can be resource-intensive. It involves querying the data type from INFORMATION_SCHEMA and parsing the result from a BLOB field.
• Altering Permitted Values: Modifying the set of permitted values for an ENUM column requires an ALTER TABLE statement. This locks the table and may trigger a restructuring operation.

Alternative Approaches

For situations with a limited number of possible values, consider using lookup tables instead of ENUM. This approach allows for more flexibility in managing permitted values and avoids the performance penalties associated with ENUM operations.

Conclusion

While ENUM provides data integrity benefits, it may not be the optimal choice for fields with a small number of possible values. Lookup tables offer a more efficient and customizable alternative in such cases.