My bad. OneToOne cannot lazy load.
There are two solutions for this:
follow Gabriels instructions here
http://blogs.hibernatingrhinos.com/nhibernate/archive/2008/11/17/lazy-loading-blobs-and-the-like-in-nhibernate.aspx
use Single Table Inheritance as described here
http://www.castleproject.org/activerecord/documentation/trunk/usersguide/typehierarchy.html
in the latter case, TextureWithImage inherits from Texture and contains the
blob. If you want to work without the blob, load Texture, if you need the
blob data, use TextureWithImage instead.
-Markus
2008/11/21 Dan Bunea <[EMAIL PROTECTED]>
> Hi Markus,
>
> We implemented it OneToOne:
>
> public class Texture{
> [OneToOne(Constrained = true,Fetch=FetchEnum.Select)]
> public TextureImage TextureImage{get; set;}//the class with blobs
> }
>
> public class TextureImage{
> [OneToOne]
> public Texture Texture { get; set; }
> }
>
> However it still loads both, and then makes the killer updates:
>
> SELECT texture0_.Id as Id21_0_, ...
> FROM Textures texture0_
> WHERE [EMAIL
> PROTECTED]',N'@p0uniqueidentifier',@p0='E68A1E62-E640-458E-92CE-9B5B00C6714A'
>
> SELECT textureima0_.Id as Id17_1_, textureima0_.ImageBinaryMin as
> ImageBin2_17_1_... texture1_.Id as Id21_0_,
> FROM TextureImages textureima0_
> left outer join Textures texture1_ on textureima0_.Id=texture1_.Id
> WHERE [EMAIL
> PROTECTED]',N'@p0uniqueidentifier',@p0='E68A1E62-E640-458E-92CE-9B5B00C6714A'
>
> If we don't add the Fetch, it will just do one SELECT which will load all,
> including the blobs, and there's not way to set Lazy=true.
>
> Thanks,
>
> Dan
>
>
> On Wed, Nov 19, 2008 at 3:12 PM, Markus Zywitza <[EMAIL PROTECTED]
> > wrote:
>
>> You attach the object to a different session. Dirty checking uses
>> first-level-cache which is tied to the session. NH must therefore perform an
>> update to assure that there has not been any changes to the object before it
>> was attached to the session.
>>
>> The "AND Version = @p3' AND Path = @p1" part is NH's optimistic locking.
>> If the data has changed, 0 rows are affected and NH detects an concurrent
>> change to data.
>>
>> To save you SQLServer from being killed you have to use a lazy loaded
>> 1-on-1-relation between object and BLOBs. See the NH FAQ blog for a tutorial
>> on this.
>>
>> -Markus
>>
>>
>> 2008/11/19 Dan Bunea <[EMAIL PROTECTED]>
>>
>>> Hi,
>>>
>>> In our application, there was a reauirement to have Guids as Ids. However
>>> we have an odd behaviour: havina a class Texture, with and Id:Guid and a
>>> property Path:string if I do something like:
>>>
>>> Texture t=null;
>>> using(SessionScope s1 = new SessionScope())
>>> {
>>> t = Texture.Find(someTexture.Id);// we added it before
>>> }
>>> using(SessionScope s1 = new SessionScope())
>>> {
>>> t.Save();
>>> }
>>>
>>> on t.Save() it will do an update such as:
>>>
>>> UPDATE Textures SET Version = @p0, Path = @p1, WHERE Id = @p2 AND Version
>>> = @p3' AND Path = @p1,
>>>
>>> Problems:
>>>
>>> 1. Since NH has dirty checking why does it even perform the update since
>>> nothing is changed.
>>> 2. Even if something has changed why isn't the update only using the Id
>>> like
>>>
>>> UPDATE Textures SET Version = @p0, Path = @p1, WHERE Id = @p2
>>>
>>> and not all the properties??
>>>
>>> Thanks,
>>>
>>> Because of problem 1 we have a multitude of UPDATES being performed some
>>> with BLOBS and it is killing the sql server.
>>>
>>> --
>>> Dan Bunea
>>> http://www.danbunea.ro
>>>
>>>
>>>
>
>
> --
> Dan Bunea
> http://www.danbunea.ro
>
>
> >
>
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