Hi,

I use session.find("From DataSource").
I get one SQL statement to retrieve all datasource rows but then I get a different SQL select for each Institution linked to a datatource.

Do you know where it could come from ?
thank you,

Here is part of my mapping:

<class name="DataSource" table="codDataSource" mutable="false">
<id name="Id" >
<generator class="increment" />
</id>
<property name="Description" />
<property name="Code" />
<many-to-one name="Institution" column="InstitutionId"/>
</class>

<class name="StatefulEntity" table="tblStatefulEntity">
<id name="Id">
<generator class="sequence">
<param name="sequence">seqObject</param>
</generator>
</id>
<bag name="Aliases" lazy="false" cascade="all-delete-orphan" inverse="true">
<key column="StatefulEntityID" />
<one-to-many class="Alias" />
</bag>
<many-to-one name="StatefulEntityType" column="StatefulEntityTypeId"/>
</class>

<joined-subclass name="Institution" extends="StatefulEntity" table="tblInstitution">
<key column="Id"/>
<property name="Name" column="InstitutionName" />
<many-to-one name="Country" column="CountryID"/>
</joined-subclass>

<class name="Alias" table="tblAlias">
<id name="Id">
<generator class="increment" />
</id>
<many-to-one name="AliasType" column="AliasTypeID"/>
<many-to-one name="StatefulEntity" column="StatefulEntityID"/>
<many-to-one name="DataSource" column="DataSourceID"/>
<property name="Value" column="Alias"/>
</class>

I understood the problem explaining it.
The problem comes from the inverse="true" on the bag list.

What is the efficient way to write a bidirectional relation ?
I cant manage to execute my query in only one call.
When I execute session.find("From DataSource"),

first SQL call:
select * from CodDataSource

then many calls:
select * from Institution where id=1
select * from Institution where id=2
select * from Institution where id=3
...

I found this in the doc:
"Note: Large Hibernate bags mapped with inverse="false" are inefficient and should be avoided; Hibernate can't create, delete or update rows individually, because there is no key that may be used to identify an individual row. "

thanks

the extra selects come from the relation. I don't think it has anything to do with the 'inverse'. Please some1 correct me if I'm wrong.

If you do a hql like this: From DataSource left join fetch Institution
it will use a join to select the institutions.

You can also make the institutions lazy loaded. Then they won't be loaded at all.