![]() So, a page of 8kB will end up storing just a few elements, therefore wasting a lot of space, both on the disk and in the database memory, as index pages could be cached in the Buffer Pool. Index pages will have a very low fill factor because the values come randomly.However, indexing random values using B+Tree causes a lot of problems: Second, the Primary Key column usually has an associated B+Tree index to speed up lookups or joins, and B+Tree indexes store data in sorted order. Every single record will need 16 bytes for the database identifier, and this impacts all associated Foreign Key columns as well. ![]() The id value being random, you can safely send it to the UI as the user would not be able to guess other identifier values and use them to see other people’s data.īut, using a random UUID as a database table Primary Key is a bad idea for multiple reasons.įirst, the UUID is huge.The chance of identifier collision is extremely low.Hence no central coordination is required. The ids can be generated by the application.The RFC 4122 specification defines five standardized versions of UUID, which are implemented by various database functions or programming languages.įor instance, the UUID() MySQL function returns a version 1 UUID number.Īnd the Java UUID.randomUUID() function returns a version 4 UUID number.įor many devs, using these standard UUIDs as a database identifier is very appealing because: While the standard 128-bit random UUID is a very popular choice, you’ll see that this is a terrible fit for a database Primary Key column.Ī universally unique identifier (UUID) is a 128-bit pseudo-random sequence that can be generated independently without the need for a single centralized system in charge of ensuring the identifier’s uniqueness. In this article, we are going to see what UUID (Universally Unique Identifier) type works best for a database column that has a Primary Key constraint. So, enjoy spending your time on the things you love rather than fixing performance issues in your production system on a Saturday night! Well, Hypersistence Optimizer is that tool!Īnd it works with Spring Boot, Spring Framework, Jakarta EE, Java EE, Quarkus, or Play Framework. Follow having a tool that can automatically detect JPA and Hibernate performance issues.
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