Migrating to Hibernate 5

Question

I am migrating an application from Hibernate 4.3 to Hibernate 5.0.1-Final I use ImplicitNamingStrategyComponentPathImpl as my hibernate.implicit_naming_strategy with Postgres 9.4.4 and my company uses hibernate.hbm2ddl.auto = update for deployment ( I know it is a bad practice but cant help it)

While the session factory initializes, it throws the below error. Apparently the generated alias is too long for Postgres. How do we go about this situation? I have tried assigning @Table(name=..) annotation to work around this it but it is getting worse as every relationship from that point gets screwd.

Caused by: org.hibernate.tool.schema.spi.SchemaManagementException: Unable to execute schema management to JDBC target [create table public.ReferenceDocumentVersion_ReferenceDocumentSourceFilesStoreDescriptor (ReferenceDocumentVersion_unid uuid not null, sourceFilesStore_filesDescriptorMap_unid uuid not null, filesDescriptorMap_KEY text not null, primary key (ReferenceDocumentVersion_unid, filesDescriptorMap_KEY))]
    at org.hibernate.tool.schema.internal.TargetDatabaseImpl.accept(TargetDatabaseImpl.java:59)
    at org.hibernate.tool.schema.internal.SchemaMigratorImpl.applySqlString(SchemaMigratorImpl.java:371)
    at org.hibernate.tool.schema.internal.SchemaMigratorImpl.applySqlStrings(SchemaMigratorImpl.java:360)
    at org.hibernate.tool.schema.internal.SchemaMigratorImpl.createTable(SchemaMigratorImpl.java:181)
    at org.hibernate.tool.schema.internal.SchemaMigratorImpl.doMigrationToTargets(SchemaMigratorImpl.java:134)
    at org.hibernate.tool.schema.internal.SchemaMigratorImpl.doMigration(SchemaMigratorImpl.java:59)
    at org.hibernate.tool.hbm2ddl.SchemaUpdate.execute(SchemaUpdate.java:129)
    at org.hibernate.tool.hbm2ddl.SchemaUpdate.execute(SchemaUpdate.java:97)
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:481)
    at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:444)
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:802)
    ... 29 more
Caused by: org.postgresql.util.PSQLException: ERROR: relation "referencedocumentversion_referencedocumentsourcefilesstoredescr" already exists
    at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2182)
    at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1911)
    at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:173)
    at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:618)
    at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:454)
    at org.postgresql.jdbc2.AbstractJdbc2Statement.executeUpdate(AbstractJdbc2Statement.java:382)
    at org.apache.tomcat.dbcp.dbcp.DelegatingStatement.executeUpdate(DelegatingStatement.java:228)
    at org.apache.tomcat.dbcp.dbcp.DelegatingStatement.executeUpdate(DelegatingStatement.java:228)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at net.bull.javamelody.JdbcWrapper.doExecute(JdbcWrapper.java:404)
    at net.bull.javamelody.JdbcWrapper$StatementInvocationHandler.invoke(JdbcWrapper.java:129)
    at net.bull.javamelody.JdbcWrapper$DelegatingInvocationHandler.invoke(JdbcWrapper.java:286)
    at com.sun.proxy.$Proxy93.executeUpdate(Unknown Source)
    at org.hibernate.tool.schema.internal.TargetDatabaseImpl.accept(TargetDatabaseImpl.java:56)
    ... 39 more

Answer 1

I have addressed the situation with a custom ImplicitNamingStrategy that truncates Hibernate generated identifiers to 64 chars (MAX length for Postgres).

Previous versions of Hibernate(4.x) have encountered the same error but they just ignores it and proceeds with initializing the SessionFactory. However, Hibernate 5.x has a new boot strap API which throws a SchemaManagementException in such cases and aborts. Hibernate logs from my test scenarios are pasted below for reference.

Hibernate 4.X

INFO: HHH000396: Updating schema
Oct 04, 2015 1:38:00 PM org.hibernate.tool.hbm2ddl.DatabaseMetadata getTableMetadata
INFO: HHH000262: Table not found: ReferenceDocumentVersionEntityWithAReallyReallyReallyLongNameBeyondPostGres
Oct 04, 2015 1:38:00 PM org.hibernate.tool.hbm2ddl.DatabaseMetadata getTableMetadata
INFO: HHH000262: Table not found: ReferenceDocumentVersionEntityWithAReallyReallyReallyLongNameBeyondPostGres
Oct 04, 2015 1:38:00 PM org.hibernate.tool.hbm2ddl.DatabaseMetadata getTableMetadata
INFO: HHH000262: Table not found: ReferenceDocumentVersionEntityWithAReallyReallyReallyLongNameBeyondPostGres
Oct 04, 2015 1:38:00 PM org.hibernate.tool.hbm2ddl.SchemaUpdate execute
ERROR: HHH000388: Unsuccessful: create table ReferenceDocumentVersionEntityWithAReallyReallyReallyLongNameBeyondPostGres (unid uuid not null, path text, primary key (unid))
Oct 04, 2015 1:38:00 PM org.hibernate.tool.hbm2ddl.SchemaUpdate execute
ERROR: ERROR: relation "referencedocumentversionentitywithareallyreallyreallylongnamebe" already exists
Oct 04, 2015 1:38:00 PM org.hibernate.tool.hbm2ddl.SchemaUpdate execute
INFO: HHH000232: Schema update complete

Hibernate 5.0.2.Final

Oct 04, 2015 1:39:16 PM org.hibernate.tool.hbm2ddl.SchemaUpdate execute
INFO: HHH000228: Running hbm2ddl schema update
Oct 04, 2015 1:39:16 PM org.hibernate.tool.schema.extract.internal.InformationExtractorJdbcDatabaseMetaDataImpl processGetTableResults
INFO: HHH000262: Table not found: ReferenceDocumentVersionEntityWithAReallyReallyReallyLongNameBeyondPostGres
Oct 04, 2015 1:39:16 PM org.hibernate.tool.schema.extract.internal.InformationExtractorJdbcDatabaseMetaDataImpl processGetTableResults
INFO: HHH000262: Table not found: ReferenceDocumentVersionEntityWithAReallyReallyReallyLongNameBeyondPostGres
Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.813 sec <<< FAILURE!
testApp(org.foobar.AppTest)  Time elapsed: 0.788 sec  <<< ERROR!
javax.persistence.PersistenceException: [PersistenceUnit: org.foobar.persistence.default] Unable to build Hibernate SessionFactory
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.persistenceException(EntityManagerFactoryBuilderImpl.java:877)
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:805)
    at org.hibernate.jpa.HibernatePersistenceProvider.createEntityManagerFactory(HibernatePersistenceProvider.java:58)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:55)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:39)
    at org.foobar.AppTest.testApp(AppTest.java:18)

Solution

• Custom ImplicitNamingStrategy

  package org.foobar.persistence;
  import org.hibernate.boot.model.naming.Identifier;
  import org.hibernate.boot.model.naming.ImplicitNamingStrategyComponentPathImpl;
  import org.hibernate.boot.spi.MetadataBuildingContext;
  
  public class PGConstrainedImplicitNamingStrategy extends ImplicitNamingStrategyComponentPathImpl {
  private static final int POSTGRES_IDENTIFIER_MAXLENGTH = 63;
  public static final PGConstrainedImplicitNamingStrategy INSTANCE = new PGConstrainedImplicitNamingStrategy();
  
  public PGConstrainedImplicitNamingStrategy() {
  
  }
  
  @Override
  protected Identifier toIdentifier(String stringForm, MetadataBuildingContext buildingContext) {
      return buildingContext.getMetadataCollector()
              .getDatabase()
              .getJdbcEnvironment()
              .getIdentifierHelper()
              .toIdentifier( stringForm.substring( 0, Math.min( POSTGRES_IDENTIFIER_MAXLENGTH, stringForm.length() ) ) );
  
  }}
  

• persistence.xml

  <properties>
      <property name="hibernate.implicit_naming_strategy" value="org.foobar.persistence.PGConstrainedImplicitNamingStrategy"/>
  </properties>
  

This is not a scalable solution at all but helps to keep the show running. The permanent solution would be to explicitly supply identifiers so that hibernate does not generate really long identifiers. - see the answer written by maaartinus

Answer 2

try to follow the Migration guide in Hibernate Documentation in this link

https://github.com/hibernate/hibernate-orm/blob/5.0/migration-guide.adoc