Planned lessonMID-021-L02

Batching inserts and updates

On This Lesson 4 topics

This lesson is planned. The outline below lists the topics it will cover. The full lesson has not been published yet.

In this lesson

send many statements to the database in few round trips.

Set hibernate.jdbc.batch_size (for example 50) and order_inserts/order_updates to group statements.
GenerationType.IDENTITY forces Hibernate to insert each row immediately to get the id, which disables insert batching.
Use a sequence (GenerationType.SEQUENCE with allocationSize matching the sequence increment) to batch inserts.
With the PostgreSQL driver, reWriteBatchedInserts=true merges inserts further (verify driver option before recording).
Flush and clear the persistence context every batch to keep memory flat.

Draft outline details

yaml

spring.jpa.properties.hibernate.jdbc.batch_size: 50
spring.jpa.properties.hibernate.order_updates: true

Why does IDENTITY stop insert batching?

Show answer

Hibernate must execute each insert at once to learn the generated id.

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