Have you used HQL, Native Query, JDBC directly? Batching in Hibernate?

Yes, I used all three approaches:

• HQL (Hibernate Query Language) — an object-oriented query language that allows writing database queries at the Java/Kotlin entity level, abstracting from the specific DBMS.

• Native Query — SQL queries written directly and executed through Hibernate when specific DBMS features need to be used or performance optimization is required.

• JDBC directly — sometimes used for simple operations or when Hibernate is not suitable, for example, to execute specific procedures or when integrating with legacy code.

Batching in Hibernate — a technique of grouping multiple insert/update operations into one batch to reduce the number of database requests and improve performance. It is configured via the hibernate.jdbc.batch_size parameter and requires proper entity configuration.

Example of batching configuration in Hibernate:

hibernate.jdbc.batch_size=50
hibernate.order_inserts=true
hibernate.order_updates=true

And an example code for batch inserts:

session.beginTransaction()
for (i in 1..1000) {
    val entity = MyEntity(data = "value $i")
    session.save(entity)
    if (i % 50 == 0) {
        session.flush()
        session.clear()
    }
}
session.transaction.commit()

This allows sending data in batches of 50 records, reducing load on the database and increasing speed.