With the default flush mode Hibernate flushes query regions before queries to run SQL against actual table data.
If two entity are connected using the join table and data is queried using a criteria Hibernate does not flush to the join table.
It flushes to the entity tables though.
The attached test case produces the SQL output
Hibernate: insert into USERS (ID, NAME) values (null, ?)
Hibernate: insert into ITEMS (ID, NAME) values (null, ?)
Hibernate: select this_.ID as ID0_1_, this_.NAME as NAME0_1_, items3_.USER_ID as USER1_, items1_.ID as ITEM2_, items1_.ID as ID2_0_, items1_.NAME as NAME2_0_ from USERS this_ inner join USER_ITEMS items3_ on this_.ID=items3_.USER_ID inner join ITEMS items1_ on items3_.ITEM_ID=items1_.ID where items1_.NAME=?
But it should flush to the USER_ITEMS table before executing the criteria query.
The commented HQL query does flush to both the entity tables and the join table.
The problem is in the org.hibernate.loader.criteria.CriteriaQueryTranslator.getQuerySpaces() method.
It returns only the entity tables.