Error: 17310: User Request Generated A Fatal Exception (AND I KNOW WHY)

Hello,

Just yesterday I implemented SqlCacheDependencies on my ASP.NET 2.0 web site for SQL Server 2005. My SQL Server 2005 database is in mode 90, mirrored with a second database server. Now I am getting Error 17310 while running very simple statements, but only on a specific table.

We have a table called "tblSchools" which, due to negligence and incompetence, has a maximum size of over 8,000. I plan on fixing that eventually, by splitting all the long varchar(2048) fields off into other tables.

I wanted to use SqlCacheDependencies on this table, for every single column. So I created a DateTime column called LastChanged and created a trigger. I am using LastChanged as a DateTime type instead of a TimeStamp/RowVersion type because I thought it would be more useful.

Here are the changes made:
---------------------------

-- Adding the column...
ALTER TABLE tblSchools
ADD
LastChanged DateTime Null
GO

-- The program uses this stored procedure to watch the "LastChanged" column.
CREATE PROCEDURE [apCacheWatchSchool]
@SchoolID int
AS
select LastChanged from dbo.tblSchools where SchoolID = @SchoolID
GO

-- Any updates on the table cause the LastChanged column to be updated with getdate()
CREATE TRIGGER [UpdateLastChanged_TS]
ON [dbo].[tblSchools]
AFTER INSERT,UPDATE
AS
BEGIN
SET NOCOUNT ON;
update [dbo].[tblSchools]
set LastChanged = getdate()
where SchoolID in (select SchoolID from inserted);
END
GO

---------------------------

After adding this column and the trigger and s-proc, any update to any row in tblSchools fails with error 17310. It CANNOT set LastChanged to anything. It has to remain NULL. I was able to perform the following operation (as long as the tblSchools.LastChanged updating trigger [UpdateLastChanged_TS] was disabled): "update tblSchools set SchoolName = 'ZZZZ' + SchoolName where SchoolID = 185" -- so, it's not some kind of row length limit. I think it's a limit on # of columns that can be dealt with. I don't really know.

I don't know where the problem is occurring. I am just telling you why. I got around the problem (temporarily) by simply having the trigger update a DateTime column in another table, and having the SqlCacheDependency watch that column in the other table. No biggie.

As for moving some of the enormous varchar columns off of tblSchools... I don't really care enough. I guess that's why it's been like this for so long.

So, my problem is fixed, I just wanted to submit this bug report so you can at least fail gracefully in the next version of SQL Server.

I have the log/txt/mdmp files available, and can provide them upon request; they're too big for this form, sorry. Please contact me at plushpuffin AT wwddfd.com if you have any questions.