If you just want to level up to Spring Boot 4 with Hibernate 7 then follow this repo

Best Performance Practices Hibernate 5/6 & Spring Boot 2

Hibernate & Spring Boot Samples

1. How To Store UTC Timezone In MySQL

Description: This application is a sample of how to store date, time, and timestamps in UTC time zone. The second setting, useLegacyDatetimeCode is needed only for MySQL. Otherwise, set only hibernate.jdbc.time_zone.

Key points:

• spring.jpa.properties.hibernate.jdbc.time_zone=UTC
• spring.datasource.url=jdbc:mysql://localhost:3306/screenshotdb?useLegacyDatetimeCode=false

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2. View Binding/Extracted Params Via Log4J 2

Description: View the prepared statement binding/extracted parameters via Log4J 2 logger setting.

Key points:

• for Maven, in pom.xml, exclude Spring Boot's Default Logging
• for Maven, in pom.xml, Add Log4j 2 Dependency
• in log4j2.xml add, <Logger name="org.hibernate.type.descriptor.sql" level="trace"/>

Output example:

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3. How To View Query Details Via DataSource-Proxy Library

Description: View the query details (query type, binding parameters, batch size, execution time, etc) via DataSource-Proxy

Key points:

• for Maven, add in pom.xml the datasource-proxy dependency
• create an bean post processor to intercept the DataSource bean
• wrap the DataSource bean via ProxyFactory and an implementation of MethodInterceptor

Output example:

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4. Batch Inserts via saveAll(Iterable<S> entities) in MySQL

Description: Batch inserts via SimpleJpaRepository#saveAll(Iterable<S> entities) method in MySQL

Key points:

• in application.properties set spring.jpa.properties.hibernate.jdbc.batch_size
• in application.properties set spring.jpa.properties.hibernate.generate_statistics (just to check that batching is working)
• in application.properties set JDBC URL with rewriteBatchedStatements=true (optimization for MySQL)
• in application.properties set JDBC URL with cachePrepStmts=true (enable caching and is useful if you decide to set prepStmtCacheSize, prepStmtCacheSqlLimit, etc as well; without this setting the cache is disabled)
• in application.properties set JDBC URL with useServerPrepStmts=true (this way you switch to server-side prepared statements (may lead to signnificant performance boost))
• in case of using a parent-child relationship with cascade persist (e.g. one-to-many, many-to-many) then consider to set up spring.jpa.properties.hibernate.order_inserts=true to optimize the batching by ordering inserts
• in entity, use the assigned generator since MySQL IDENTITY will cause insert batching to be disabled
• in entity, add @Version property to avoid extra-SELECT statements fired before batching (also prevent lost updates in multi-request transactions). Extra-SELECT statements are the effect of using merge() instead of persist(); behind the scene, saveAll() uses save(), which in case of non-new entities (entities that have IDs) will call merge(), which instruct Hibernate to fire a SELECT statement to make sure that there is no record in the database having the same identifier
• pay attention on the amount of inserts passed to saveAll() to not "overwhelm" the Persistence Context; normally the EntityManager should be flushed and cleared from time to time, but during the saveAll() execution you simply cannot do that, so if in saveAll() there is a list with a high amount of data, all that data will hit the Persistence Context (1st Level Cache) and will remain in memory until the flush time; using relatively small amount of data should be ok (in this example, each batch of 30 entities run in a separate transaction and Persistent Context)
• the saveAll() method return a List<S> containing the persisted entities; each persisted entity is added into this list; if you just don't need this then it is created for nothing

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5. Batch Inserts Via EntityManager (MySQL)

Description: This application is a sample of batching inserts via EntityManager in MySQL. This way you can easily control the flush() and clear() cycles of the Persistence Context (1st Level Cache) inside the current transaction. This is not possible via Spring Boot, saveAll(Iterable<S> entities), since this method executes a single flush per transaction. Another advantage is that you can call persist() instead of merge() - this is used behind the scene by the SpringBoot saveAll(Iterable<S> entities) and save(S entity).

If you want to execute a batch per transaction (recommended) then check this example.

Key points:

• in application.properties set spring.jpa.properties.hibernate.jdbc.batch_size
• in application.properties set spring.jpa.properties.hibernate.generate_statistics (just to check that batching is working)
• in application.properties set JDBC URL with rewriteBatchedStatements=true (optimization for MySQL)
• in application.properties set JDBC URL with cachePrepStmts=true (enable caching and is useful if you decide to set prepStmtCacheSize, prepStmtCacheSqlLimit, etc as well; without this setting the cache is disabled)
• in application.properties set JDBC URL with useServerPrepStmts=true (this way you switch to server-side prepared statements (may lead to signnificant performance boost))
• in case of using a parent-child relationship with cascade persist (e.g. one-to-many, many-to-many) then consider to set up spring.jpa.properties.hibernate.order_inserts=true to optimize the batching by ordering inserts
• in entity, use the assigned generator since MySQL IDENTITY will cause insert batching to be disabled
• in your DAO layer, flush and clear the Persistence Context from time to time (e.g. for each batch); this way you avoid to "overwhelm" the Persistence Context
• if is not needed, then ensure that Second Level Cache is disabled via spring.jpa.properties.hibernate.cache.use_second_level_cache=false

Output example:

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6. How To Batch Inserts Via JpaContext/EntityManager In MySQL

Description: Batch inserts via JpaContext/EntityManager in MySQL.

Key points:

• in application.properties set spring.jpa.properties.hibernate.jdbc.batch_size
• in application.properties set spring.jpa.properties.hibernate.generate_statistics (just to check that batching is working)
• in application.properties set JDBC URL with rewriteBatchedStatements=true (optimization for MySQL)
• in application.properties set JDBC URL with cachePrepStmts=true (enable caching and is useful if you decide to set prepStmtCacheSize, prepStmtCacheSqlLimit, etc as well; without this setting the cache is disabled)
• in application.properties set JDBC URL with useServerPrepStmts=true (this way you switch to server-side prepared statements (may lead to signnificant performance boost))
• in case of using a parent-child relationship with cascade persist (e.g. one-to-many, many-to-many) then consider to set up spring.jpa.properties.hibernate.order_inserts=true to optimize the batching by ordering inserts
• in entity, use the assigned generator since MySQL IDENTITY will cause insert batching to be disabled
• the EntityManager is obtain per entity type via, JpaContext#getEntityManagerByManagedType(Class<?> entity)
• in DAO, flush and clear the Persistence Context from time to time; this way you avoid to "overwhelm" the Persistence Context
• if is not needed, then ensure that Second Level Cache is disabled via spring.jpa.properties.hibernate.cache.use_second_level_cache=false

Output example:

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7. How To Exploit Session-Level Batching (Hibernate 5.2 Or Higher) In MySQL

Description: Batch inserts via Hibernate session-level batching (Hibernate 5.2 or higher) in MySQL.

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