Can someone explain this behaviour?

Hello All,
The following script is reproducing the problem assuming you have
Northwind database on the server.
Please note it gives you the error message on line 12.
USE tempdb
GO
sp_addlinkedserver 'Test17'
GO
sp_setnetname 'Test17', @.@.SERVERNAME
GO
IF EXISTS (SELECT 1 FROM dbo.sysobjects WHERE id =
object_id(N'[dbo].[This_works]') and OBJECTPROPERTY(id, N'IsProcedure') = 1)
DROP PROCEDURE [dbo].[This_works]
GO
CREATE PROCEDURE This_works
@.UseLinkedServer bit = 0
-- WITH RECOMPILE -- Does not help
AS
SET NOCOUNT ON
IF @.UseLinkedServer = 1 -- Linked Server
BEGIN
IF EXISTS (SELECT 1 FROM dbo.sysobjects where id =
object_id(N'[dbo].[Orders_TMP]') and OBJECTPROPERTY(id, N'IsUserTable')
= 1)
DROP TABLE dbo.Orders_TMP
SELECT * INTO dbo.Orders_TMP FROM Test17.Northwind.dbo.Orders
END
ELSE -- Local
BEGIN
IF EXISTS (SELECT 1 FROM dbo.sysobjects where id =
object_id(N'[dbo].[Orders_TMP]') and OBJECTPROPERTY(id, N'IsUserTable')
= 1)
DROP TABLE dbo.Orders_TMP
SELECT * INTO dbo.Orders_TMP FROM Northwind.dbo.Orders
SELECT 1 FROM dbo.Orders_TMP WHERE 1 = 2 -- Why do I need this line?
END
BEGIN TRANSACTION
Select 'Line 25'
SELECT COUNT(*) FROM dbo.Orders_TMP
COMMIT
go
IF EXISTS (SELECT 1 FROM dbo.sysobjects WHERE id =
object_id(N'[dbo].[This_does_not]') and OBJECTPROPERTY(id,
N'IsProcedure') = 1)
DROP PROCEDURE [dbo].[This_does_not]
GO
CREATE PROCEDURE This_does_not
@.UseLinkedServer bit = 0
-- WITH RECOMPILE -- Does not help
AS
SET NOCOUNT ON
IF @.UseLinkedServer = 1 -- Linked Server
BEGIN
IF EXISTS (SELECT 1 FROM dbo.sysobjects where id =
object_id(N'[dbo].[Orders_TMP]') and OBJECTPROPERTY(id, N'IsUserTable')
= 1)
DROP TABLE dbo.Orders_TMP
SELECT * INTO dbo.Orders_TMP FROM Test17.Northwind.dbo.Orders
END
ELSE -- Local
BEGIN
IF EXISTS (SELECT 1 FROM dbo.sysobjects where id =
object_id(N'[dbo].[Orders_TMP]') and OBJECTPROPERTY(id, N'IsUserTable')
= 1)
DROP TABLE dbo.Orders_TMP
SELECT * INTO dbo.Orders_TMP FROM Northwind.dbo.Orders
--SELECT 1 FROM dbo.Orders_TMP WHERE 1 = 2 -- Why do I need this line?
END
BEGIN TRANSACTION
Select 'Line 25'
SELECT COUNT(*) FROM dbo.Orders_TMP
COMMIT
GO
PRINT 'This_works'
EXECUTE This_works 0
PRINT ' '
PRINT 'This_does_not'
EXECUTE This_does_not 0
Thanks for any help or hint,
Igor Raytsin
Igor Raytsin (igorray@.sympatico.ca) writes:
> The following script is reproducing the problem assuming you have
> Northwind database on the server.
> Please note it gives you the error message on line 12.
I think I understand what's going on. Since you drop and recreate the
table, the next reference to the table after its recreation will cause
a recompilation of the procedure. If that SELECT is in a transaction, you
have a problem, because SQL Server then wants to talk with the linked server
to verify the table. (Deferred name resolution does not apply to linked
tables.)
Erland Sommarskog, SQL Server MVP, esquel@.sommarskog.se
Books Online for SQL Server SP3 at
http://www.microsoft.com/sql/techinf...2000/books.asp
|||Igor
In addition
Inside the transaction spesify name of the database and it will work
BEGIN TRANSACTION
Select 'Line 25'
SELECT COUNT(*) FROM Northwind.dbo.Orders_TMP
COMMIT
Perhaps SQL Server verified the new table (SELECT * INTO) by SELECT which
is was remarted in the second example
(Deferred name resolution does not apply to linked
> tables.)
Erlan, I think it has nothing to do with a linked servers it does a creation
on the local server and not a linked one.
Or if I did not understand you , can you please elaborate the explanation?
"Erland Sommarskog" <esquel@.sommarskog.se> wrote in message
news:Xns96295474102Yazorman@.127.0.0.1...
> Igor Raytsin (igorray@.sympatico.ca) writes:
> I think I understand what's going on. Since you drop and recreate the
> table, the next reference to the table after its recreation will cause
> a recompilation of the procedure. If that SELECT is in a transaction, you
> have a problem, because SQL Server then wants to talk with the linked
server
> to verify the table. (Deferred name resolution does not apply to linked
> tables.)
>
> --
> Erland Sommarskog, SQL Server MVP, esquel@.sommarskog.se
> Books Online for SQL Server SP3 at
> http://www.microsoft.com/sql/techinf...2000/books.asp
|||Uri Dimant (urid@.iscar.co.il) writes:
> Erlan, I think it has nothing to do with a linked servers it does a
> creation on the local server and not a linked one. Or if I did not
> understand you , can you please elaborate the explanation?
It's correct that the actual execution path does not touch the linked
server. However, the procedure is recompiled as a whole, and the procedure
includes a reference to linked table. And when the recompilation occurs
in a transaction, that transaction becomes a distributed transaction,
but this is not handled well.
Erland Sommarskog, SQL Server MVP, esquel@.sommarskog.se
Books Online for SQL Server SP3 at
http://www.microsoft.com/sql/techinf...2000/books.asp
|||Erland
Ok, I got it, but how do you explain that by adding a name of the database
within a tranasction (which is becamed distributed ) it began to work?
"Erland Sommarskog" <esquel@.sommarskog.se> wrote in message
news:Xns96298185A423CYazorman@.127.0.0.1...
> Uri Dimant (urid@.iscar.co.il) writes:
> It's correct that the actual execution path does not touch the linked
> server. However, the procedure is recompiled as a whole, and the procedure
> includes a reference to linked table. And when the recompilation occurs
> in a transaction, that transaction becomes a distributed transaction,
> but this is not handled well.
>
> --
> Erland Sommarskog, SQL Server MVP, esquel@.sommarskog.se
> Books Online for SQL Server SP3 at
> http://www.microsoft.com/sql/techinf...2000/books.asp
|||Uri Dimant (urid@.iscar.co.il) writes:
> Ok, I got it, but how do you explain that by adding a name of the
> database within a tranasction (which is becamed distributed ) it began
> to work?
I got the same error message when I made your replacement. I suspect
that you had inadvertently created an Orders_TMP in the Northwind
database. But Igor's script runs from tempdb. Under this scenario
there is no need for recompilation.
Erland Sommarskog, SQL Server MVP, esquel@.sommarskog.se
Books Online for SQL Server SP3 at
http://www.microsoft.com/sql/techinf...2000/books.asp