Thank you. It does produce one query but runs 10 times slower than the
very simmillar query with DataReader
this is the query with DataReader
command.CommandText = "SELECT u.name, u.year, p.name FROM User u JOIN
Position p ON u.position_id=p.id;";
using (SQLiteDataReader dataReader = command.ExecuteReader())
{
while (dataReader.Read())
{
User user = new User(dataReader.GetString(0),
dataReader.GetInt32
(1), dataReader.GetString(2));
users.Add(user);
}
}
and with NH
IList<User> users =
session.CreateQuery("select u from User u join
fetch u.RealPosition").List<User>();
return users;
On 100000 rows in User it runs within less than 1 sec with the
DataReader.
With the HQL you suggested NH is producing almost exact same SQL as
the manual query above but runs in 12-13 sec.
I realize it is not exactly equal test as the one with DataReader
doesn't care for the Position objects but is there something I can do
to get a comparable performance form NH?
On Nov 2, 6:21 pm, Fabio Maulo <[email protected]> wrote:
> select u from User u join fetch u.RealPosition
>
> 2009/11/2 mitirino <[email protected]>
>
>
>
>
>
>
>
> > Hi,
>
> > I have many-to-one for User and Position and when I want to load the
> > users it makes one select to get all the users and then one select per
> > user to get the position for each one.
>
> > Is there any way to avoid this and actually load everything with one
> > select?
>
> > Thank you
>
> > ----
>
> > IList<User> items = session.CreateQuery("from User").List<User>();
>
> > ---
>
> > <class name="User" table="User" >
> > <id name="Id" column="id">
> > <generator class="native" />
> > </id>
> > <property name="Name" column="name" />
> > <property name="Year" column="year" />
> > <many-to-one name="RealPosition"
> > class="Position"
> > column="position_id" />
> > </class>
>
> > ----
>
> > <class name="Position" table="Position" >
> > <id name="Id" column="id">
> > <generator class="native" />
> > </id>
> > <property name="Name" column="name" />
> > </class>
>
> --
> Fabio Maulo- Hide quoted text -
>
> - Show quoted text -
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