java - When does Hibernate create a new entry from a FK to a non-PK column? -

suppose have:

-- table_1 -------------------   |id      | property_x | data | ------------------------------  -- table_2 ------------------------ |id      | property_x | moar_data | ----------------------------------- 

and table_1 has fk property_x table_2.property_x
(why not table_2.id? idk, project :( )

the hbms this:

<!-- table 1 --> <hibernate-mapping package="com.example">     <class name="table1" table="table_1">         <id column="id" type="integer" name="id">             <generator class="native"/>         </id>         <many-to-one class="table2" fetch="join" name="table2" not-null="false">             <column name="property_x" />         </many-to-one>     </class> </hibernate-mapping> 

and

<!-- table 2 --> <hibernate-mapping package="com.example">     <class name="table2" table="table_2">         <id column="id" type="integer" name="id">             <generator class="native"/>         </id>         <property column="property_x" name="propertyx" type="string"/>     </class> </hibernate-mapping> 

the thing want save object table1 using session.save(objtable1), without creating new table2 entry in db, , without loading either. have done in past creating new object, , setting primary key values, leaving else blank, , not letting update table2 table, not pk >_<.

now, suppose have in table_2 entry with id=5, property_x="ex". when following...

// example method public void savesomething(sessions sess) {     table1 table1 = new table1();     table2 table2 = new table2();      table2.setpropertyx("ex");     table1.settable2(table2);      sess.save(table1); } 

... creates new entry, i'm guessing it's because pk (id) table2 not set.

my question is, how hibernate decide create new entry in db fk object?, , there way avoid on hbm files?

it's cascade anotation, if dont want table 2 created in db, dont set child, if want table 2 updated, need table 2 id.

alternatively, can set cascade="none" in hbm of table 1 or cascade="update", table 2 still wont updated without id.