CHAR(16) or VARCHAR(36): What's the Best Way to Store GUIDs in MySQL?

How to Optimize GUID Storage in MySQL

When storing GUIDs (Globally Unique Identifiers) in MySQL tables, the optimal approach depends on the required functionality and efficiency considerations.

CHAR(16) Binary

For maximum space efficiency, store GUIDs as CHAR(16) binary. This approach utilizes a 16-byte raw binary representation of the GUID, providing a direct and compact storage format.

Benefits of CHAR(16) Binary:

• Reduced storage space utilization compared to VARCHAR(36).
• Fast indexing and retrieval, as the binary representation aligns well with MySQL's internal data handling.

VARCHAR(36)

Alternatively, you can store GUIDs as VARCHAR(36). This format represents the GUID as a 36-character hexadecimal string.

Benefits of VARCHAR(36):

• Easier human readability, as it is a textual representation.
• Can be directly compared and sorted as strings.

Integer Conversion

As suggested by some DBAs, it is possible to convert GUIDs to a 4-byte unsigned integer using a hashing function or GUID decomposition algorithms. However, this approach sacrifices the uniqueness guarantee of GUIDs, as collisions may occur.

Conclusion

The recommended storage method depends on the specific requirements of the application. For maximum storage efficiency and performance, CHAR(16) binary is the optimal choice. If human readability or textual comparison is essential, VARCHAR(36) can be considered.

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