Is MySQL ENUM Really Worth the Performance Trade-Off?

MySQL ENUM Performance Considerations

When working with data that has a limited range of possible values, it may be tempting to consider using an ENUM data type. However, it's crucial to understand the potential performance implications of this choice.

Performance Penalty of ENUM

Contrary to popular belief, using ENUM for situations with 5-10 possible values can actually come with a significant performance penalty. This is particularly evident in operations such as:

• Querying permitted values for drop-down menu population: To obtain the list, you must query the ENUM data type from INFORMATION_SCHEMA and extract it from a BLOB field.
• Altering permitted values: This requires an ALTER TABLE statement, which locks the table and potentially triggers a restructure, resulting in delays.

Alternative Approach: Lookup Tables

Instead of relying on ENUM, a more efficient approach is to utilize lookup tables. These tables store possible values and can be related to the main table via a foreign key.

Use Cases for ENUM

While ENUM is generally not recommended for performance-sensitive operations, it can still be beneficial in specific scenarios:

• Simplicity: ENUM provides a straightforward way to enforce data integrity and prevent invalid values.
• Storage efficiency: For very small sets of values (e.g., Boolean values), ENUM can be more efficient than using lookup tables.
• Documentation: ENUMs can serve as a form of documentation, clearly indicating the range of acceptable values.

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