Please see the attached HHH-13067.zip file for a self-contained example, runnable using mvn clean test.

There are two entity classes, the Parent references the Child using @ManyToMany(fetch=FetchType.EAGER). Suppose that a Parent instance references more than one Child instance.

The session.createCriteria(Parent.class).list() legacy Criteria API query is translated into an SQL query using LEFT OUTER JOIN, so the Parent rows are returned multiple times.

The following alternatives all produce the correct result

• by executing two separate SELECT statements:
  • Using the new JPA CriteriaQuery API to build the query
  • Using FetchType.LAZY instead of FetchType.EAGER in the entity definition
  • Adding @Fetch(FetchMode.SUBSELECT) to the entity definition
• by filtering the result set for distinct values:
  • Adding criteria.setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY) to the query

Suggestion: when the legacy Criteria API builds the SQL query, it should default to FetchMode.SUBSELECT if the @ManyToMany relation is defined with FetchType.EAGER.