Hi Fabio,
thanks for your reply.
> Remove all specification about "lazy" and "fetch" from your mappings.For who
> are new in NH the best way is :
> -write your mapping specifying less as possible; string length when is
> different than 255, scale+precision for double, after that write only what
> is required.
Ok, but well... I started with less as possible. Afterwards I added
the different options for lazy loading.
> -study how work with eager loading trough HQL and/or CriteriaAPI
I think I did. I know, that I don't want to load in eager mode, as I
don't need the additional loaded Informations. I'm using the
CriteriaAPI.
> When your app is working:
> Go to reference and study "Improving performance"
I think I did. I've learned a lot about fetching strategies and
created the ideal sql statement via the criteriaAPI. But I can't find
anything about my basic problem:
Why is it fetching some data from the many-to-one references directly
after executing my 'ideal' statement? Is this standard behaviour? Can
I prevent him loading the other data, as I don't need this data right
now?
> Take a look to this mapping
>
> <class name="OrdenDeCompra">
> <id name="Id">
> <generator class="hilo"/>
> </id>
> <many-to-one name="EmpresaCompra"/>
> <many-to-one name="OrganizacionCompra"/>
> <property name="Comentarios"/>
>
> <property name="Numero" length="35"/>
> <property name="Nombre" length="50"/>
> <property name="Usuario" length="30"/>
> <property name="FechaCreacion"/>
> <property name="FechaEnvio"/>
> <property name="FechaPublicacion"/>
> <property name="Estado"/>
> <many-to-one name="Moneda"/>
> <many-to-one name="MetodoDespacho"/>
> <many-to-one name="FormaPago"/>
> <many-to-one name="RazonSocial"/>
> <many-to-one name="EmpresaVenta"/>
> <many-to-one name="OrganizacionVenta"/>
> <list name="Lineas" access="field.camelcase" cascade="all" inverse="true">
> <key column="IDOC" on-delete="cascade"/>
> <list-index column="NUMLINEAOC"/>
> <one-to-many class="OrdenDeCompraLinea"/>
> </list>
> </class>
Thanks for your help.
I've got something like this
[...]
<many-to-one name="ext" class="MyAssembly.Ext, MyAssembly">
<column name="person" />
<column name="type" />
</many-to-one>
[...]
> heavy to write no ? ;)
Obviously not. But I still don't understand why nhibernate does
something like this:
<EditedLogfile>
2009-03-18 14:44:19,664 [11] INFO NHibernate.Loader.Loader - SELECT
[...] FROM myDB.workertype this_
left outer join myDB.contract contract2_ on this_.ID=contract2_.BV and
this_.CLASS=contract2_.BVTYP
left outer join myDB.company company3_ on
contract2_.PARTNER=company3_.ID and
contract2_.PARTNERTYP=company3_.CLASS
inner join myDB.Department dep1_ on this_.ID=dep1_.BV and
this_.CLASS=dep1_.BVTYP
WHERE ( this_.CLASSID='external') AND LOWER(name) LIKE '%smith%' and
department = 42
<pause>
This would be enough. This statement is perfectly alright. But the
workertype-class has got some other many-to-one associations and loads
them like the following... for each record of my query above! :(
</pause>
2009-03-18 14:44:21,410 [11] INFO NHibernate.Loader.Loader - SELECT
[...] FROM myDB.workertype work0_ WHERE work0_.ID=:p0 and
work0_.CLASS=:p1
2009-03-18 14:44:26,023 [11] INFO NHibernate.Loader.Loader - SELECT
[...] FROM myDB.Person p0_
left outer join myDB.Image img1_ on p0_.ID=img1_.ID and
p0_.CLASS=img1_.CLASS
left outer join myDB.Person person2_ on img1_.ID=person2_.ID and
img1_.CLASS=person2_.CLASS
WHERE p0_.ID=:p0 and p0.CLASS=:p1 and ( p0_.CLASSID='worker')
2009-03-18 14:44:26,070 [11] INFO NHibernate.Loader.Loader - SELECT
[...] FROM myDB.Person worker0_
left outer join myDB.Image img1_ on worker0_.ID=img1_.ID and
worker0_.CLASS=img1_.CLASS
left outer join myDB.Person person2_ on img1_.ID=person2_.ID and
img1_.CLASS=person2_.CLASS
WHERE worker_.ID=:p0 and worker0_.CLASS=:p1 and
( worker0_.CLASSID='worker')
2009-03-18 14:44:26,662 [11] INFO NHibernate.Loader.Loader - SELECT
[..] FROM myDB.Person person0_
left outer join myDB.Image img1_ on person0_.ID=img1_.ID and
person0_.CLASS=img1_.CLASS
left outer join myDB.Person person2_ on img1_.ID=person2_.ID and
img1_.CLASS=person2_.CLASS
WHERE person0_.ID=:p0 and person0_.CLASS=:p1
2009-03-18 14:44:27,426 [11] INFO NHibernate.Loader.Loader - SELECT
[...] FROM myDB.Person ext0_
left outer join myDB.Image img1_ on ext0_.ID=img1_.ID and
ext0_.CLASS=img1_.CLASS
left outer join myDB.Person person2_ on img1_.ID=person2_.ID and
img1_.CLASS=person2_.CLASS
WHERE ext0_.ID=:p0 and ext0_.CLASS=:p1 and
( ext0_.CLASSID='external')
</EditedLogfile>
Thanks in advance. Still looking for explanations.
> 2009/3/18 Fred F. <[email protected]>
>
>
>
>
>
>
>
> > Hi folks!
>
> > I'm using NHibernate v2.0.50727 and I'm quite uncertain about many-to-
> > one and lazy loading, although I've read several blogs about this
> > topic.
>
> > I've got following scenario:
>
> > Class A has a one-to-many relation to class B (bag collection) and B
> > has got a many-to-one relation to class C. Class A an B do have some
> > other many-to-one relations to other classes (lets say Relation R1 and
> > Relation R2) which are not important for my query.
>
> > Class A (1)--->(n) Class B (n) ---> (1) Class C
>
> > Default is lazy=true, but I'm creating my criteria with an left outer
> > join to the classes, so I only need one query for this case. I can see
> > the correct query in my logs. This query returns a collection of
> > records. I can test this query in my sql-client and everything is
> > fine. So far so good.
>
> > But:
>
> > For _each_ of my records nhibernate sends additional queries to the
> > database. And it seems that it queries for the related objects which
> > are related to class A and B by many-to-one relations (Relation R1 and
> > R2). This additional references are completely unnecessary in this
> > case and they are not used in this part of the application.
>
> > My question:
>
> > Why is nhibernate quering for these additional objects although nobody
> > uses them? I've tried several different options in my many-to-one
> > relations like
>
> > outer-join="false"
> > lazy="proxy" (I suppose I'm not aware of the effect)
> > fetch="select"/fetch="join"
>
> > I've added lazy="false" to all classes.
>
> > How can I prevent nhibernate to load these not needed objects? It has
> > quite an impact on my performance level.
>
> > Thanks in advance!
> > Fred F.
>
> --
> Fabio Maulo- Zitierten Text ausblenden -
>
> - Zitierten Text anzeigen -
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"nhusers" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/nhusers?hl=en
-~----------~----~----~----~------~----~------~--~---
