Sorry I still do not understand. This is my C# code:
return from oi in NHibernateSession.Current.Query<BlaInteraction>()
select new BlaViewModel
{
...
NoPublications = oi.Publications.Count(),
...
};
I use Count() which means I do not need to populate the publications
of oi. So the following ‘sub query’ (?) which is part of the select
part of the generated sql (slightly adapted):
select cast(count(*) as INT) from RelationshipStatementPublications
publicatio21_, Publication publicatio22_ inner join Statements
publicatio22_1_ on publicatio22_.StatementId=publicatio22_1_.DBId
where publicatio21_.StatementId = 22762181 and
publicatio21_.PublicationId=publicatio22_.StatementId
is far too complicated. The joins are just not necessary. Hence,
something like this sub query:
select cast(count(*) as INT) from RelationshipStatementPublications
publicatio21_ where publicatio21_.StatementId = 22762181
would be enough.
Could you please elaborate on the separate read-only class? Thanks.
Christian
On Sep 12, 1:12 pm, John Davidson <[email protected]> wrote:
> The big question is why does nhibernate think that it needs to join
> statement just to count the publications and how can I prevent this?
>
> This is because you are telling it to always do the join so that you can
> navigate the hierarchy.
>
> If you do not want to navigate the hierarchy for your connoting then you
> need a separate class to do so that does not have the join mapped. It should
> also be marked as readonly so that it does not interfere with your other
> processes.
>
> John Davidson
>
> On Mon, Sep 12, 2011 at 7:29 AM, csetzkorn <[email protected]> wrote:
> > Thanks for your reply. I am sorry but can you please elaborate on this
> > as I do not understand? I have this inheritance structure:
>
> > Statement -> Publication
>
> > Statement->X
>
> > In statement I have an IList of Publication so that any Statement
> > (e.g. X above) can be associated with a publication (obviously it
> > wouldn’t necessarily make sense to associate a publication with
> > another publication).
>
> > My fluent nhibernate mapping for statement is:
>
> > mapping.HasManyToMany(x =>
> > x.Publications).Table("RelationshipStatementPublications")
>
> > I have tried things like:
>
> > mapping.HasManyToMany(x =>
>
> > x.Publications).Table("RelationshipStatementPublications").Fetch.Select().ExtraLazyLoad();
>
> > but this did not change anything.
>
> > The big question is why does nhibernate think that it needs to join
> > statement just to count the publications and how can I prevent this?
> > IMHO it ‘thinks’ that it needs to populate the whole publication (i.e.
> > join the parent: statement) ...
>
> > Thanks.
>
> > Christian
>
> > On Sep 9, 4:20 pm, John Davidson <[email protected]> wrote:
> > > So your Publications class is mapped with a join to Statements. If you
> > want
> > > your query to not include that inner join then you need to create another
> > > class, say RoPublications, that is set as read only and does not have the
> > > join, then use that class for your count.
>
> > > John Davidson
>
> > > On Fri, Sep 9, 2011 at 10:51 AM, csetzkorn <[email protected]> wrote:
> > > > Hi,
>
> > > > Thanks for the reply. I copy and paste the question on SA below. Not
> > > > sure why it is incomplete - please let me know why. Thanks!
>
> > > > I am using this query:
>
> > > > return from oi in NHibernateSession.Current.Query<BlaInteraction>()
> > > > select new BlaViewModel
> > > > {
> > > > ...
>
> > > > NoPublications = oi.Publications.Count(),
>
> > > > ...
> > > > };
>
> > > > BlaInteraction contains an IList of publications (i.e. entities). To
> > > > determine the number of publications one does not really need to do
> > > > all the joins for a publication. Can I prevent nhibernate from using
> > > > joins in the generated sql (e.g. using projection???) somehow?
>
> > > > Thanks.
>
> > > > Christian
>
> > > > PS:
>
> > > > This is what NH produces (slightly adapted):
>
> > > > select cast(count(*) as INT) from
> > > > RelationshipStatementPublications publicatio21_, Publication
> > > > publicatio22_ inner join Statements publicatio22_1_ on
> > > > publicatio22_.StatementId=publicatio22_1_.DBId where
> > > > publicatio21_.StatementId = 22762181 and
> > > > publicatio21_.PublicationId=publicatio22_.StatementId
>
> > > > This is what would be sufficient:
>
> > > > select cast(count(*) as INT) from
> > > > RelationshipStatementPublications publicatio21_ where
> > > > publicatio21_.StatementId = 22762181
>
> > > > On Sep 9, 2:24 pm, John Davidson <[email protected]> wrote:
> > > > > If you really want an answer here please post the details in your
> > message
> > > > > rather than in StackOverflow. I checked StackOverflow and your query
> > > > there
> > > > > is incomplete. Please try again.
>
> > > > > John Davidson
>
> > > > > On Fri, Sep 9, 2011 at 9:01 AM, csetzkorn <[email protected]>
> > wrote:
> > > > > > Hi experts,
>
> > > > > > Could you please be so kind and have a look at this:
>
> >http://stackoverflow.com/questions/7359783/prevent-unnecessary-cross-.
> > > > ..
>
> > > > > > Thanks.
>
> > > > > > Christian
>
> > > > > > --
> > > > > > 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.
>
> > > > --
> > > > 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.
>
> > --
> > 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.
>
>
--
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.
