I'm running an online workshop on the 15th of September about High-Performance SQL. Notice the calls to the uuid_generate_v4 PostgreSQL function which is used to assign the UUID identifier values. "insert into post (title, id) values (?, ?)" Now, when persisting 3 Post entities, Hibernate generates the following SQL statements: The attribute is used to customize the UUID generation strategy via the uuid_gen_strategy_class parameter value which takes the fully-qualified class name of the .UUIDGenerationStrategy interface implementation. The uuid2 strategy stands for .UUIDGenerator which we want to use instead of the legacy .UUIDHexGenerator that’s registered under the uuid name in Hibernate. To provide the PostgreSQLUUIDGenerationStrategy to our Post entity, we have to use the Hibernate-specific = "post") Now, we can call the uuid_generate_v4 function to get a variant 4 UUID based on IETF RFC 4122 specification. In our case, 4 stands for variant 4 (random) generator strategy.īecause we are using PostgreSQL, we also need to create the uuid-ossp extension before using the UUID-specific functions:ĬREATE EXTENSION IF NOT EXISTS "uuid-ossp" The getGeneratedVersion method defines what type of UUID we are generating, according to the IETF RFC 4122 standard. Throw new IllegalArgumentException("Can't fetch a new UUID") ResultSet resultSet = statement.executeQuery( Statement statement = connection.createStatement() Hibernate generates the following SQL INSERT statement: tTitle("High-Performance Java Persistence") Getters and setters omitted for brevity However, few might know that GenerationType.AUTO can be used for UUID identifiers as = "post") When using JPA, we can use the GenerationType.AUTO strategy of the annotation to assign numerical identifier automatically, based on an IDENTITY column, a SEQUENCE or the infamous TABLE generator. Now, let’s see how we can map the Post entity so that the UUID identifier be auto-generated for us. The Post entity has a UUID identifier and a title. In this article, we are going to see how to use a UUID entity identifier that is auto-generated by Hibernate either in the JVM or using database-specific UUID functions. 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. Return Long.toHexString(MSB | ng.nextLong()) + Long.toHexString(MSB | ng.Follow having a tool that can automatically detect JPA and Hibernate performance issues. NumberGenerator = ng = new SecureRandom() Private static volatile SecureRandom numberGenerator = null Maxim: Copied from UUID implementation :) Note that I'm not generating a UUID, instead just a random 32 bytes hex string in the most efficient way I could think of. Ended up writing something of my own based on UUID.java implementation.
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