Hello, Steven!
Sounds interesting! Why don't you open an improvement issue
on https://nhibernate.jira.com?
Regards,
RP
On Tuesday, January 22, 2013 10:08:24 AM UTC, Steven Xi wrote:
>
> I was started choosing orm systems since few weeks ago and little bit
> struggle in use NH or EF.
> I know there was a big argument around which one's better, which i'm not
> quite interested to discuss here, but I did test some basic performance of
> both.
> I have to say I really like the flexibility NH provided, but I still bit
> concern about the performance, especially materialization of NH is much
> slower than EF.
> Although I temporary chose EF as the Orm of my currently project, but I
> hope that can switch back to NH once the performance has been improved.
>
> But, anyway, after reviewing and profile NH code for few hours, I tried to
> make some small change to improve the performance,
> here's what I found.
>
> When NH materialize Linq query, it uses dynamicinvoke to construct object,
> which is obviously slow. After change the constructor call delegate (both
> in Linq\ResultTransformer and Linq\ExpressionToHqlTranslationResults) from
> Delegate type to Func<object[],object> type ( for item transformer only as
> testing, but list transformer should be same), the time costed *reduced
> to less than 50%.*
> *
> *
> Here's some test result, retrieve 200001 rows, simple entity.
> Entity (single table in db):
>
> public class Person
> {
> [Key]
> public virtual int PersonId { get; protected set; }
>
> [StringLength(100)]
> public virtual string FirstName { get; set; }
>
> [StringLength(100)]
> public virtual string LastName { get; set; }
> }
>
>
>
> Query(Session is status less):
>
> int agr = 0;
> foreach (var pp in session.Query<Person>().Where(p => p.PersonId
> > 0)
> .Select(p => new { p.PersonId, p.FirstName, p.LastName }))
> //.Take(100))
> {
> agr++;
> }
> return agr;
>
>
> Before changing this query took 1.2 seconds (while EF took 0.2 second) on
> my machine ( SQL express, i5 3.1Ghz 4GB win7).
> After changing this query took 0.5 to 0.6 seconds.
>
> This is the quick change I can discover so far.
> Some other place I've looked is NH 's retrieve row/column data and
> converting types designed little bit too heavy, but changing this requires
> changing the code structur, which I dont have to do yet. Something I can
> think about to be small change is it uses lots of Converto.Toxxx() method
> which I believe to be a performance impact, and also, after it do a
> conversion (in most case is unnecessary) it do a boxing again, so there's
> some extra steps can be removed.
>
> Hope it helps.
>
> Regards,
> Steven
>
>
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