Perform VACUUM FULL with JPA

问题

I'm using a PostgreSQL DB and I would like to start VACUUM FULL using JPA EntityManager.

Version 1

public void doVacuum(){
  entityManager.createNativeQuery("VACUUM FULL").executeUpdate()
}

throws TransactionRequiredException

Version 2

@Transactional
public void doVacuum(){
  entityManager.createNativeQuery("VACUUM FULL").executeUpdate()
}

throws PersistenceException "VACUUM cannot run inside a transaction block"

Version 3

public void doVacuum(){
  entityManager.createNativeQuery("VACUUM FULL").getResultList()
}

vacuum is performed but after that I get PersistenceException "No results"

What is the correct way to start this sql command?

回答1:

As Alay Hay mentioned, using the underlying connection will work:

public void doVacuum(){
  org.hibernate.Session session = entityManager.unwrap(org.hibernate.Session);
  org.hibernate.internal.SessionImpl sessionImpl = (SessionImpl) session;  // required because Session doesn't provide connection()
  java.sql.Connection connection = sessionImpl.connection();
  connection.prepareStatement("VACUUM FULL").execute()
}

来源：https://stackoverflow.com/questions/46982548/perform-vacuum-full-with-jpa