hibernate and delete all

What is the best way to delete all rows in a table in Hibernate?

If I iterate ov开发者_如何学Cer a collection and call session.delete() it's not performing to my knowledge.

If I use another option session.createQuery("delete ...") it doesn't affect persistence context.

When I should use these methods if there is no better variant?

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You can use HQL for truncate table

public int hqlTruncate(String myTable){
    String hql = String.format("delete from %s",myTable);
    Query query = session.createQuery(hql)
    return query.executeUpdate();
}

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• if you don't have anything to cascade, use the HQL delete DELETE FROM enityName
• if you have cascades, iterate the collection and delete each one individually.

The problem lies in the fact that hibernate handles cascades internally, rather than leaving this to the database. So sending a query won't trigger the internal cascades, hence you will have inconsistencies / orphans.

If performance is so crucial (after all it's not everyday that one truncates a table), then you can have more than 1 HQL delete for each cascade - i.e. handling the cascades manually.

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String stringQuery = "DELETE FROM tablename";
Query query = session.createQuery(stringQuery);
query.executeUpdate();