Ayende @ Rahien

jdn commented on NHibernate Mapping -

Wed, 22 Apr 2009 23:30:16 GMT

Well, okay. I did not get that from the comment(s) that you made, you are usually very clear and direct in what you say. I don't see how one gets from 'there is no way to actually create a SQL query' to (paraphrasing) 'you can't get good performance from a SQL query in a generic way.' Apologies if I misconstrued anything you said, never my intention. I believe that you can do it in SQL with acceptable performance margins, but that is highly dependent on context and how one defines 'acceptable', so I won't harp on that here. Thanks.

Ayende Rahien commented on NHibernate Mapping -

Wed, 22 Apr 2009 06:20:22 GMT

jdn, I meant, there is no generic way to do it in SQL that has acceptable performance margins

jdn commented on NHibernate Mapping -

Tue, 21 Apr 2009 16:38:34 GMT

I didn't 'forget' anything. I was responding to "There is no way to actually create a SQL query that would do that." to Mark. It is possible to write the query for what he asked about. To 'generalize' it, you would dynamically generate the SQL (which would require other work, of course) that needed to be executed. Note, I'm not saying this is a good thing, but it is possible.

Ayende Rahien commented on NHibernate Mapping -

Tue, 21 Apr 2009 16:33:15 GMT

Jdn, a) you forgot that you may have different properties for different entitites. that is, not all entities would have Amount, how do you handle that? b) try to generalize this scenario for a 10 entities scenario, see what happens

jdn commented on NHibernate Mapping -

Tue, 21 Apr 2009 16:29:31 GMT

select o.* from [Order] o left join CCPayments on CCPayments.ID = o.PaymentID and o.PaymentType = 'CC' left join WirePayments on WirePayments.ID = o.PaymentID and o.PaymentType = 'Wire' where CCPayments.Amount = 100 or WirePayments.Amount = 100 Given the data Mark listed (3 orders, 2 in CC, 1 in Wire), this returns the correct two rows. What am I missing?

Ayende Rahien commented on NHibernate Mapping -

Tue, 21 Apr 2009 16:26:06 GMT

Jdn, Please try to formulate that query.

jdn commented on NHibernate Mapping -

Tue, 21 Apr 2009 16:09:39 GMT

"select order o where o.Payment.Amount = 100" "There is no way to actually create a SQL query that would do that." There isn't? What am I missing? The query is pretty trivial. Or do you mean there isn't a way to tell NHibernate how to do it?

Ayende Rahien commented on NHibernate Mapping -

Tue, 21 Apr 2009 14:13:20 GMT

Kyle, Wait for tomorrow :-)

Ayende Rahien commented on NHibernate Mapping -

Tue, 21 Apr 2009 14:12:56 GMT

Craig, By their positions The first is the type, the second is the id.

Kyle Baley commented on NHibernate Mapping -

Tue, 21 Apr 2009 14:10:16 GMT

What if you wanted to have a collection of payments on the order?

Craig Quillen commented on NHibernate Mapping -

Tue, 21 Apr 2009 14:04:42 GMT

How does it know which of the

Daniel Fernandes commented on NHibernate Mapping -

Tue, 21 Apr 2009 08:03:15 GMT

@Ayende The second I posted my comment I thought I was way off as I've got only small understanding of the NHibernate codebase :) The reason why I think

Ayende Rahien commented on NHibernate Mapping -

Tue, 21 Apr 2009 07:43:08 GMT

Daniel, Fairly easy? Not really. Try extremely hard. Just for kicks, try to write a SQL statement that can do that, they try to generalize this for the whole concept. As for being able to query that, any is supposed to be used for special purposes, not for anything, and if you want to query that, just query it from the other side.

Daniel Fernandes commented on NHibernate Mapping -

Tue, 21 Apr 2009 07:25:05 GMT

@Ayende Isn't it a big limitation that from NH point of view a

Ayende Rahien commented on NHibernate Mapping -

Tue, 21 Apr 2009 07:17:31 GMT

Mark, No, we cannot do that. There is no way to actually create a SQL query that would do that.

mark commented on NHibernate Mapping -

Tue, 21 Apr 2009 07:11:18 GMT

one question about

CaliCoder commented on NHibernate Mapping -

Tue, 21 Apr 2009 05:34:29 GMT

nice post!

josh commented on NHibernate Mapping -

Tue, 21 Apr 2009 04:28:29 GMT

i don't like those scenarios, but I do like how nhib can handle it.