ehm... are you creating the DB using NH ?
are you validating the schema using NH ?
on-delete="cascade" works as espected but you have to check what NH think
you have in the DB with what you really have;
also you have to check the <cascade> configuration because even when you
have the ON DELETE constraint (hard cascade) the delete operation may become
"inefficient" due soft-cascade (logic cascade).
in practice... if you have on-delete="cascade" and you are 100% that the
child entity does not have any other soft-cascade with others entities, on
delete, be sure that your <cascade> value does not includes neither "delete"
nor "delete-orphans".
btw
session.CreateQuery("from Child c where c.Parent.Id =
:theParent").ExecuteUpdate();
do the same work you done with Ado.NET
On Mon, Apr 4, 2011 at 5:45 PM, Dzyann Leleur <[email protected]> wrote:
> Hi Roger, thanks for your answer.
>
> That the parent know its children so far has been relevant for the deletion
> case, which is needed. Now i do Understand if you guys consider this
> shouldn't be handled by Nhibernate. That is why I sent an email here. I have
> all the Web Application working with Nhibernate, and when I found this
> problem, the easiest solution for me was just to use ado.net, that is why
> in my initial email I asked if the best would be an approach like just do
> the sql sentence (ado.net or such).
> I asked help here because I wanted to try keep all the application using
> Nhibernate, but if for cases like this doesn't make sense, is fine.
>
> I read what you said about the inverse=true, but I have certain confusion
> with it.
> On the link you gave me (
> http://www.nhforge.org/doc/nh/en/index.html#performance-collections-oneshotdelete)
> says:
> one-shot-delete apply to collections mapped inverse="true".
>
> Now from what I have been reading on internet this doesn't work, It
> actually behaves like you say. So maybe the documentation is wrong? or i
> just totally misunderstood what it says?
>
> Regards,
>
> Dzy.-
>
>
>
> On Mon, Apr 4, 2011 at 4:52 PM, Roger Kratz <[email protected]>wrote:
>
>> <<I am not going to perform operations like you put, for each item of the
>> collection, we are just doing queries over them.>>
>>
>> Instead of letting the parent knows thousands of children, isn't enough if
>> the child knows its parent?
>>
>>
>> Anyhow....
>>
>> Having inverse=true means that this side doesn't own the collection.
>> AFAIK, this means that theCollection.Clear() won't do anything from a NH
>> perspective.
>>
>> Try hql delete, plain ado.net or, as already mentioned,
>> on-delete="cascade".
>>
>>
>>
>> ________________________________
>> Från: [email protected] [[email protected]] för Dzyann
>> Leleur [[email protected]]
>> Skickat: den 4 april 2011 20:04
>> Till: [email protected]
>> Ämne: Re: [nhusers] Delete Cascade taking a long time
>>
>> Hi,
>> The Domain, is designed as it is, is a very specific case, that doesn't
>> happen much. And actually, is just an applicatin to migrate data, so the
>> user doesn't have this problem of having such massive associations.
>>
>> I am not going to perform operations like you put, for each item of the
>> collection, we are just doing queries over them.
>>
>> What I want to know if the way I set the deletion was correct.
>> This is what i have (without the on-delete="cascade")
>>
>> <hibernate-mapping xmlns="urn:nhibernate-mapping-
>> 2.2" default-access="property" auto-import="true" default-cascade="none"
>> default-lazy="true">
>> <class xmlns="urn:nhibernate-mapping-2.2" mutable="true" name="Query,
>> Domain, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"
>> table="`Query`">
>> <id name="Id" type="System.Int32, mscorlib, Version=4.0.0.0,
>> Culture=neutral, PublicKeyToken=b77a5c561934e089">
>> <column name="Id" />
>> <generator class="identity" />
>> </id>
>> <bag cascade="all-delete-orphan" inverse="true" name="NasLocations"
>> mutable="true">
>> <key>
>> <column name="Query_id" />
>> </key>
>> <one-to-many class="NASLocation, Domain, Version=1.0.0.0,
>> Culture=neutral, PublicKeyToken=null" />
>> </bag>
>> <bag cascade="all-delete-orphan" inverse="true" name="MetadataItems"
>> mutable="true">
>> <key>
>> <column name="Query_id" />
>> </key>
>> <one-to-many class="MetadataItem, Domain, Version=1.0.0.0,
>> Culture=neutral, PublicKeyToken=null" />
>> </bag>
>>
>> Mapping for QueryMetadataItem and NasLocations relation with Query:
>>
>> <many-to-one class="Query,Domain, Version=1.0.0.0, Culture=neutral,
>> PublicKeyToken=null" foreign-key="Query_id" name="Query">
>> <column name="Query_id" />
>> </many-to-one>
>>
>> I am deleting the items as follows:
>> query.NasLocations.Clear();
>> query.MetadataItems.Clear();
>>
>> And then removing the Query itself.
>> The NasLocations items do not get deleted at all, and the MetadataItems
>> get delete one by one.
>>
>> I did this following the link Roger gave me. I don't see what I am doing
>> wrong.
>>
>> Regards,
>>
>> Dzy.-
>>
>>
>> On Mon, Apr 4, 2011 at 2:48 PM, Fabio Maulo <[email protected]<mailto:
>> [email protected]>> wrote:
>> public class Country
>> {
>> ...
>> ...
>> public IEnumerable<Person> People{get; private set;}
>> }
>>
>> using(var session = sf.OpenSession())
>> {
>> var china = s.QueryOver<Country>().Where(x=> x.Name ==
>> "China").SingleOrDefault();
>> foreach(var person in china.People)
>> {
>> DoSomethingButComeBackTomorrowToSeeResult();
>> }
>> }
>>
>> The link that Roger gave you is correct what is incorrect is the design of
>> the domain.
>>
>> On Mon, Apr 4, 2011 at 2:33 PM, Dzyann Leleur <[email protected]<mailto:
>> [email protected]>> wrote:
>> Hi Fabio,
>> What do you mean with that trying to map a collection that big is wrong?
>> Do you mean like I shouldn't use NHibernate? Or that the collection
>> shouldn't be that big?
>> The collection is being created by a service, we don't have a choice but
>> having that collection, there is no other way. The service is not working
>> with Nhibernate to create the data. We are using Nhibernate for the User
>> interface part, that creates queries on the data. But has the option to
>> delete them too.
>>
>> When I saw how Nhibernate was behaving, I thought that maybe I shouldnt
>> try to delete the collection with Nhibernate and just do it with SQL, but I
>> wanted to see different options.
>> I am going to try the "on-delete="cascade"", but, was the approach I
>> implemented following the link:
>>
>> http://www.nhforge.org/doc/nh/en/index.html#performance-collections-oneshotdelete
>> that Roger gave me, wrong?
>>
>> Regards,
>>
>> Dzy.-
>>
>> On Sun, Apr 3, 2011 at 10:04 PM, Fabio Maulo <[email protected]
>> <mailto:[email protected]>> wrote:
>> try to map a collection with 95K items is simple wrong and nothing more.
>> btw you can use on-delete="cascade"
>>
>>
>> On Fri, Apr 1, 2011 at 6:23 PM, Dzyann <[email protected]<mailto:
>> [email protected]>> wrote:
>> Hi,
>>
>> I have a an entity Query that has a lot of items Metadata in a
>> relation "one-to-many".
>> When I delete the Query, I want all its childs to be delete too, so I
>> set cascade to all-delete-orphan.
>>
>> The items get deleted, but it takes a lot of time. The query can have
>> many items, lets say 95k items.
>> I checked out with the SQL Profiler to see what was going on, and I
>> saw that each Metadata Item is getting deleted one by one like:
>>
>> exec sp_executesql N'DELETE FROM MyDatabase.dbo.[QueryMetadata] WHERE
>> Id = @p0',N'@p0 int',@p0=302401
>>
>> This takes time, and produces a bad user experience. I would like to
>> hear out any recommendations.
>> Maybe is better if I delete the items with a sql sentence?
>>
>> Thanks in advance for your help!
>>
>> Dzy.-
>>
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>>
>>
>> --
>> Fabio Maulo
>>
>>
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