If you know that you're going to need to serialize ALL of the children
of a graph, you could session.Get() all levels of the graph at the
start of the call. NH will then link the entities up for you and avoid
return trips to the DB. Unless your entities are HUGE (blob size
binary data) then generally returning 10,000 rows in one query is much
faster than numerous round trips for fewer entities.
If the entities are from different tables, and you only need to load
some of them this becomes more tricky, but still can be accomplished
by multiple outer joins in a criteria/hql query. Even if you don't use
the results, running the query should speed up your graph traversal.
On Mon, Sep 22, 2008 at 4:12 PM, gatapia <[EMAIL PROTECTED]> wrote:
>
> Hi,
>
> I need to serialise a data tree however the performance of this is
> understandable poor as all children must be fetched prior to
> serialisation. I was looking for a better performing way of doing
> this.
>
> Currently before serialising a child collection I check wether the
> collection is empty by:
>
> if(NHibernate.NHibernateUtil.IsInitialized(Children)) { return
> Children.Count() > 0; }
> NHibernate.IQuery q = GetSession().CreateFilter(Children, "Select
> count(*)");
> return Convert.ToInt32(q.UniqueResult()) > 0;
>
> This greatly improves performance over a straight call to
> Children.Count() but I still think there must be a better way of doing
> this.
>
> If an Entity has 2+ children collections can I get their count in one
> database call?
>
> Any other suggestions?
>
> Thanks
>
> Guido Tapia
> >
>
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