session.CreateCriteria(typeof(ForthTable)).List(); sesson.CreateCriteria(typeof(Level)).List();
Two queries, and you loaded everything. On Tue, Jan 20, 2009 at 2:27 PM, Thomas Koch <[email protected]> wrote: > > Hi Will and Ayende - thanks for the replies. :-) > > I know there are Select N+1 going on here. The main cause of all > theses selects is that I have three different classes that constitutes > a tree with three levels: Level1 -> Level2 -> Level3. > > I have 20 rows at Level1, 40 rows at Level2 and 300 rows at Level3. > Each level has a list of the next level - mapped as a bag in the .hbm > files. Level2 and Level3 each have a list of objects pointing back to > themselves. Moreover the lowest level (Level3) has two many-to-many > collections to a fourth class (table). In fact it is this lowest level > that is causing most of the selects. > > As far as I understand I can only put fetch="join" on one property on > a mapped class and with all these references on Level2 and Level3 it > seems to me that its usability is limited in my scenario. > > The workaround I have been thinking of is to create a class for all > ten tables, many-to-many tables included, and then simply do ten > LoadAll(). I would then build object graph manually instead of having > NHibernate do it. > > Is that what you guys would do in a similar situation? > > Regards > Thomas > > > > > On 20 Jan., 20:07, Ayende Rahien <[email protected]> wrote: > > You have a select N+1, and it is a problem.It is pretty common to do > > preloading on app startup, but that should be even close to that number. > > You need to optimize your startup queries. > > > > On Tue, Jan 20, 2009 at 2:01 PM, Thomas Koch <[email protected]> wrote: > > > > > Hi - I have a discussion with some co-workers regarding the number of > > > hits that NHibernate is performing against our database. > > > > > Our setup: We are developing ASP.NET applications using NHibernate 2.0 > > > for the data access. > > > > > We have a web-application containing static information stored in 7 > > > inter-connected classes based on 10 underlying tables. This static > > > information is needed all the time, thus we load all of this into > > > memory when the application starts. > > > > > Using NHibernate to create and fill this object hierarchy we get 1100 > > > selects being sent to the database. This takes around 6 seconds to > > > complete. > > > > > My co-workers feel that this is an accident waiting to happed, whereas > > > I myself consider this less of problem - after all we only do this > > > once on application start-up. > > > > > What do you think? Is 1100 select statements on application start > > > something to be afraid of? > > > > > Any opinion/advice is appreciated. > > > > > Regards > > > Thomas > > > --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
