Java: Spring Boot, Spring Data JPA, Hibernate

Hibernate updates the schema from the entity (ddl-auto=update, catalog introspection), then Spring Data saves and counts rows. The code is the same against the original database and against MachSQL; only the address changes.

The only change

JDBC_URL=jdbc:postgresql://old-postgres:5432/app
JDBC_URL=jdbc:postgresql://machsql-host:5432/app

Nothing else changes: not the code, not the driver, not its version, not the SQL.

Versions

• Java 25 (LTS)
• Spring Boot 4.1.2 (Hibernate ORM 7 and the PostgreSQL JDBC driver from its dependency management)

Run

export JDBC_URL=jdbc:postgresql://machsql-host:5432/app DB_PASSWORD=...
mvn -q spring-boot:run

Expected output: inserted todo <id>, <n> open.

Source

The program as it is kept and tested in the Mach Database for PostgreSQL repository; highlighted lines read the connection setting.

src/main/resources/application.properties

# The only line that changes is the host inside JDBC_URL.
spring.datasource.url=${JDBC_URL}
spring.datasource.username=${DB_USER:app}
spring.datasource.password=${DB_PASSWORD}
spring.jpa.hibernate.ddl-auto=update
spring.main.web-application-type=none

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>4.1.2</version>
    <relativePath/>
  </parent>

  <groupId>example.machsql</groupId>
  <artifactId>java-spring-boot</artifactId>
  <version>1.0.0</version>

  <properties>
    <java.version>25</java.version>
  </properties>

  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
      <groupId>org.postgresql</groupId>
      <artifactId>postgresql</artifactId>
      <scope>runtime</scope>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>
</project>

src/main/java/example/Application.java

package example;

import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;

/** Spring Boot with Spring Data JPA and Hibernate. */
@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

    @Bean
    CommandLineRunner demo(TodoRepository todos) {
        return args -> {
            Todo todo = todos.save(new Todo("write the examples"));
            long open = todos.countByDoneFalse();
            System.out.printf("inserted todo %d, %d open%n", todo.getId(), open);
        };
    }
}

src/main/java/example/Todo.java

package example;

import jakarta.persistence.Entity;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;
import jakarta.persistence.Table;

@Entity
@Table(name = "jpa_todo")
public class Todo {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String title;

    private boolean done;

    protected Todo() {}

    public Todo(String title) {
        this.title = title;
    }

    public Long getId() {
        return id;
    }

    public String getTitle() {
        return title;
    }

    public boolean isDone() {
        return done;
    }
}

src/main/java/example/TodoRepository.java

package example;

import org.springframework.data.jpa.repository.JpaRepository;

public interface TodoRepository extends JpaRepository<Todo, Long> {
    long countByDoneFalse();
}