![]() MySQL v8.0.0 (2016) added the function UUID_TO_BIN() which does the same thing: SELECT uuid_to_bin("f7c26694-aac6-4333-91c9-72c4441430e2") AS uuid_bin +-+Īnd it's easy to perform the reverse here: SELECT lower( insert( insert( insert( insert( Even better, comparison and sorting will use the numeric value of the column, which will perform much better than a string.Īll versions of MySQL can use UNHEX() and REPLACE() to do this: SELECT UNHEX(REPLACE("f7c26694-aac6-4333-91c9-72c4441430e2", "-", "")) AS unhex_replace +-+ ![]() The BINARY type isn't affected by the table character set (such as utf8mb4), it uses the binary character set and collation. If we strip the hyphens and convert the remaining 32 characters to BINARY, we can store UUIDs in only 16 bytes. UUIDs are supposed to be only 16 bytes, can't we do better? Binary UUID columns Universally unique identifiers (UUIDs) are 128-bit (16-byte) numbers that are designed to be globally unique, and as a result they make for great primary keys. So keep in mind that selecting the right data type can prevent future headaches and allow for an efficient and easily scalable database.Why You Should Use UUIDs for Your Primary Keys While other types are valid options, associated pitfalls must be evaluated to ensure proper usage. However, it is worth noting that unsigned big integers are the most reliable and performant data type to use. Ultimately, the choice of data type for primary keys will depend on the database's specific needs and how it is designed. This approach is not ideal, as the primary keys are better used for unique identification of each record in the database while leaving the obfuscation to a separate column. Some developers might use UUIDs or GUIDs to obfuscate the primary key when exposed in public APIs or URLs. ULIDs are a new option for sorted GUIDs that are worth considering. If you want to use a string as a primary key, you should look for a UUID or GUID that is time-sorted, so all new records go to the end of the table, rather than in the middle. Additionally, the B-tree may have to be rebalanced if insertions occur in the middle of the table. The problem with these types of data is their size, which means the indexes of the table grow enormously as a result of them. Choosing strings as primary keysĬhoosing a string data type, such as a UUID or a GUID, as a primary key can be tempting, but it has potential pitfalls. Additionally, they allow for auto-incrementing, which preserves a natural order for the records, ensuring that the primary key B-tree isn't split unnecessarily. ![]() Unsigned big integers provide virtually infinite room to grow, which is essential because running out of primary key space is a significant issue for databases. The recommended practice for primary keys is to use unsigned big integers. As such, it is essential to choose the right data type that meets the database's requirements and avoid potential pitfalls that could lead to performance issues or other problems down the road. The primary key serves as a unique identifier for each record in a table, and it is a critical element in database design. What data type you should use for primary keys in MySQLĪn essential decision when designing a database schema is choosing the data type for the primary key.
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