Comments on: NHibernate queries & sql server execution plans

By: Yesterday's news | NHibernate parameter sizes controversy

Yesterday's news | NHibernate parameter sizes controversy — Wed, 28 Oct 2009 15:46:52 +0000

[...] 03/10 Claudio publishes a post on his blog, in which he explains the issue and the solutions he found so [...]

By: Database Myths: Stored Procedures vs. Ad Hoc Queries | Coding Efficiency

Database Myths: Stored Procedures vs. Ad Hoc Queries | Coding Efficiency — Mon, 03 Aug 2009 16:52:05 +0000

[...] Source: MSDN1, MSDN2, MSDN3, Blog [...]

By: SentientPC

SentientPC — Mon, 27 Jul 2009 03:36:17 +0000

Thanks for the great article, I found this very problem my self. Also, in my case, my data column was defined as varchar(15) and using .SetString(“MyCol”, “MyVal”) created parameter as nvarchar(5) as you described. However, this also caused the query plan to perform an Index Scan rather than Index Seek and added 200ms, higher IO and CPU cost to my query. This was all due to the conversion of nvarchar to varchar.

By: NHibernate 2.1.0 beta 2 « TDD developer

NHibernate 2.1.0 beta 2 « TDD developer — Sun, 21 Jun 2009 17:16:17 +0000

[...] This version contains a fix for bug that cause some problem with MS Sql server execution plans (more details here). [...]

By: Dario Quintana

Dario Quintana — Tue, 17 Mar 2009 22:57:06 +0000

I know are deep dive inside SqlServer internals, doesn’t mean they could make things easier for us, remember the people are developing NHibernate need a little help from the Sql Server people too, and so far they are complicating more and more some features, and we are mort developers too, they can hide some details. Because remember, this is an specific Sql Server problem. But you know, is easier to change an OSS-ORM than this kind of RDBMS.

BTW, I know, an ORM should help, it that is the reason that prepare_sql will be true in NH 2.1.

By: makka

makka — Tue, 17 Mar 2009 22:36:39 +0000

These details are a deep dive inside SqlServer internals.
An ORM should help a mort developer, like me, and hide these details.
I’m trying to understand why the attributes length & sql-type are not used to create better SqlCommand by SqlClientDriver

By: Dario Quintana

Dario Quintana — Tue, 17 Mar 2009 04:56:41 +0000

SqlServer to me, has a complicated way to solve some the problems, including this and pagination too. I would be nice to see these problem solved as another RDBMS do.

By: makka

makka — Mon, 16 Mar 2009 08:27:03 +0000

I don’t believe this is a real NHibernate’s parameter problem but as we know a limitation of MsSqlServer we should care about it.
If NHibernate would use Length attribute by-default in MsSql2005Dialect this issue wouldn’t exists.
Sorry what do you mean by “MsSQL-server have solved the pagination issue” ?

By: Fabio Maulo

Fabio Maulo — Sun, 15 Mar 2009 22:22:47 +0000

Are you sure about the title of this post ?

“NHibernate’s parameter problem” ?

I think the real problem is the way MsSQL-server are choosing plans because others RDBMS (as Firebird) don’t have the same problem.
Identically situation is for the way MsSQL-server have solved the pagination issue.

Perhaps somebody should write something to MsSQL team.

By: NHibernate, SQL Server, performance, piani di esecuzione, … - Il blog di Andrea Benedetti

Wed, 11 Mar 2009 12:25:16 +0000

[...] ha tirato fuori una possibile soluzione che ha prontamente postato sul suo blog inglese (qui) – attendo anche una versione in italiano su UGI [...]