Generate a database update scripts with Hibernate/Spring

Question

I have a project where we use to rely on hibernate to update database with changes (hibernate.hbm2ddl.auto=update)... even on prod... I am migrating that to use liquibase instead.

My only concern is that not everyone is a sql guru in my team, so I am looking for a simple way to generate the sql script that hibernate would have done if it was updating the database.

We are all using Intellij IDEA but couldn't find this feature.

Do you know any tool capable of doing that?

Thank you

Answer 1

Full schema dumped with mvn hibernate4:export and pom.xml:

<!-- To export full DDL schema as it seeing by Hibernate run: mvn hibernate4:export -->
<plugin>
    <!-- http://mydevnotes.nicus.it/2013/03/generate-ddl-with-maven-jpa-hibernate-4.html -->
    <groupId>de.juplo</groupId>
    <artifactId>hibernate4-maven-plugin</artifactId>
    <version>1.1.0</version>
    <configuration>
        <hibernateDialect>org.hibernate.dialect.MySQLDialect</hibernateDialect>
        <delimiter>;</delimiter>
        <target>SCRIPT</target>
        <outputFile>${project.build.directory}/schema-hibernate4-maven-plugin.sql</outputFile>
    </configuration>
</plugin>

You may copy necessary parts.

With LiquiBase you have more options by generating diff between DB and Hibernate mapping file / annotations by mvn liquibase:diff and corresponding part in pom.xml:

<plugin>
    <groupId>org.liquibase</groupId>
    <artifactId>liquibase-maven-plugin</artifactId>
    <version>${liquibase.version}</version>
    <configuration>
        <changeLogFile>${basedir}/src/main/resources/sql/master.xml</changeLogFile>
        <propertyFile>${liquibase.profile}</propertyFile>
        <promptOnNonLocalDatabase>false</promptOnNonLocalDatabase>
        <logging>debug</logging>
        <outputFileEncoding>utf-8</outputFileEncoding>
        <driver>com.mysql.jdbc.Driver</driver>
        <!-- <url>jdbc:mysql://localhost:3306/app?autoReconnect=true&amp;characterEncoding=utf-8</url> -->
        <!-- <username>AAAAAA</username> -->
        <!-- <password>BBBBBB</password> -->
        <defaultSchemaName>testx</defaultSchemaName>
        <changelogSchemaName>testx</changelogSchemaName>

        <!-- For mvn liquibase:updateSQL -->
        <migrationSqlOutputFile>migration.sql</migrationSqlOutputFile>

        <referenceUrl>hibernate:spring:com.app.domain?dialect=org.hibernate.dialect.MySQLDialect</referenceUrl>
        <diffChangeLogFile>changelogDiff.xml</diffChangeLogFile>
        <diffTypes>tables,views,columns,indexes,foreignkeys,primarykeys,uniqueconstraints</diffTypes>
    </configuration>
    <dependencies>
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-jpa</artifactId>
            <version>${spring-data.version}</version>
        </dependency>
        <!-- https://github.com/liquibase/liquibase-hibernate/wiki -->
        <dependency>
            <groupId>org.liquibase.ext</groupId>
            <artifactId>liquibase-hibernate4.2</artifactId>
            <version>3.5</version>
        </dependency>
    </dependencies>
</plugin>

You may read my notes about http://tips.defun.work/liquibase.html

Answer 2

To actually display the scripts generated by Hibernate from your mappings, you can:

• as suggested by Andrei I, add those two lines to your application.properties:

  spring.jpa.hibernate.ddl-auto=validate
  logging.level.org.hibernate.tool.hbm2ddl=DEBUG
  

Source for Hibernate 4.3: SchemaUpdate.java

• or manually generate those scripts with the following code:

  LocalSessionFactoryBuilder sessionFactory = new LocalSessionFactoryBuilder(dataSource);
  sessionFactory.scanPackages("your.package.containing.entities");
  Dialect dialect = new MySQL5Dialect(); // select your dialect
  DatabaseMetadata metadata = new DatabaseMetadata(dataSource.getConnection(), dialect, sessionFactory);
  List<SchemaUpdateScript> scripts = sessionFactory.generateSchemaUpdateScriptList(dialect, metadata);
  
  Formatter formatter = FormatStyle.DDL.getFormatter();
  for (SchemaUpdateScript script : scripts) {
     System.err.println(formatter.format(script.getScript()) + ";");
  }
  

You can even add this code in a @Test, as described here.

Good luck!