Do ENUMs in MySQL Offer a Performance Advantage?

Performance Considerations for Enums in MySQL

In situations where a field has only a limited range of distinct values, database designers often consider using the ENUM data type. While ENUMs offer certain benefits, it's important to assess their performance implications before utilizing them.

Performance Penalty with ENUMs

Contrary to popular belief, ENUMs may actually hinder performance in certain operations:

• Retrieving Permitted Values: To obtain the list of acceptable values in an ENUM, queries must access the INFORMATION_SCHEMA table and decode a BLOB field. This can be a time-consuming process.
• Modifying Permitted Values: Altering the set of values in an ENUM necessitates an ALTER TABLE statement, which locks the table and could potentially require a database restructure. This operation can be resource-intensive and time-consuming.

Alternative Approach:

For fields with a small number of distinct values, lookup tables can be a more efficient solution. Lookup tables allow for easy retrieval and modification of permitted values without incurring the performance penalties associated with ENUMs.

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