JPA/Hibernate5 通过序列名称获取序列 nextval

Question

How can I get sequence nextval in JPA or Hibernate 5 by sequence name ?

I have sequence the following TEST_SEQ in Oracle DB and ANOTHER_NAME_SEQ in Postgresql DB.

I need a method with following signature

public Long getSequenceByName(String sequenceName){}

And when I call this method it must return nextval from DB which is now used.

I have a couple of ideas, but they are not suitable.

1) Store native query for each DB in properties and write method like this:

@Value("${query}")//"SELECT {name}.NEXTVAL FROM DUAL"
private StringQuery;

public Long getSequenceByName(String sequenceName){
    uery q = em.createNativeQuery(StringQuery.replace("{name}", sequenceName));
    return (java.math.BigDecimal) q.getSingleResult();
  }

But I need to store the query string with placeholders and replace placeholder to sequence name, store query for each DB.

2) Create entity with only one field @Id . Insert entity and getId(sequence value).

But if in different DB is different sequence names - ???

3) Use this . But It for hibernate 3 and I don't know if this is a good approach.

EDIT:

I try this solution:

@Component
public class SequenseRepository {

    @PersistenceContext
    private EntityManager em;

    @Transactional
    public Long getID(final String sequenceName) {
        final List<Long> ids = new ArrayList<>(1);

        Session session = em.unwrap(Session.class);
        session.doWork(connection -> {
            DialectResolver dialectResolver = new StandardDialectResolver();
            Dialect dialect =  dialectResolver.resolveDialect((DialectResolutionInfo) connection.getMetaData());
            PreparedStatement preparedStatement = null;
            ResultSet resultSet = null;
            try {
                preparedStatement = connection.prepareStatement( dialect.getSequenceNextValString(sequenceName));
                resultSet = preparedStatement.executeQuery();
                resultSet.next();
                ids.add(resultSet.getLong(1));
            }catch (SQLException e) {
                throw e;
            } finally {
                if(preparedStatement != null) {
                    preparedStatement.close();
                }
                if(resultSet != null) {
                    resultSet.close();
                }
            }
        });

        return ids.get(0);
    }
}

And I get exeption:

java.lang.ClassCastException: oracle.jdbc.driver.OracleDatabaseMetaData cannot be cast to org.hibernate.engine.jdbc.dialect.spi.DialectResolutionInfo


Answer 1

I found solution thanks to this article enter link description here

    public interface SequenceRepository {
    int getNext(String sequenceName);
   }

and implementation for each DB:

@Profile("oracle")
@Component("oracleSequenceRepository")
public class OracleSequenceRepository implements SequenceRepository{

    private final DataSource dataSource;

    @Autowired
    public OracleSequenceRepository(@Qualifier("dataSource") DataSource dataSource) {
        this.dataSource = dataSource;
    }

    @Transactional(readOnly = true)
    @Override
    public int getNext(String sequenceName) {
        AbstractSequenceMaxValueIncrementer incr = new OracleSequenceMaxValueIncrementer(this.dataSource, sequenceName);
        return incr.nextIntValue();
    }
}

and

@Profile("postgre")
@Component("postgresSequenceRepository")
public class PostgreSequenceRepository implements SequenceRepository{

    private final DataSource dataSource;

    @Autowired
    public PostgreSequenceRepository(@Qualifier("dataSource") DataSource dataSource) {
        this.dataSource = dataSource;
    }

    @Transactional(readOnly = true)
    @Override
    public int getNext(String sequenceName) {
        AbstractSequenceMaxValueIncrementer incr = new PostgresSequenceMaxValueIncrementer(this.dataSource, sequenceName);
        return incr.nextIntValue();
    }
}

Answer 2

Try this:

// Get metadata from connection
DatabaseMetaData metaData = connection.getMetaData();

// Create adapter between MetaData and DialectResolutionInfo
DialectResolutionInfo info = new DatabaseMetaDataDialectResolutionInfoAdapter(metaData);

// Resolve dialect
DialectResolver dialectResolver = new StandardDialectResolver();
Dialect dialect = dialectResolver.resolveDialect(info);

// Use it
System.out.println(dialect.getSelectSequenceNextValString(sequenceName));