临时表在SSIS中立即下降

Question

I have successfully deployed many SSIS packages (in SQL Server 2008 R2).

I have discovered an issue that is stumping me. Examine the basic following flow.

In 'Download Files from FTP' I pick up the new files I want to operate on and download them to my local drive, saving the picked up files so they can be iterated upon in the Process Each File foreach container.

In 'Create Temp Table' I am creating a temp table as such:

IF not exists (SELECT * FROM tempdb.dbo.sysobjects WHERE name='##tempProcessFiles' and xtype='U')
CREATE TABLE ##tempProcessFiles
(
--my columns
)
GO

In 'Truncate Temp Table' I am doing:

TRUNCATE TABLE ##tempProcessFiles

Basically, I pick up some files, create a temp table and then loop through each file, loading the necessary junk to my database. In order to make sure everything runs smoothly, I truncate the temp table on each iteration so I have a fresh table to work with. On the very last step of this package, I drop the temp table. I also drop the temp table OnError.

The problem is, when I schedule this guy, create temp table executes fine but once it reaches 'truncate temp table', it throws an exception saying the temp table does not exist. Specifically:

Executing the query "TRUNCATE TABLE ##tempProcessFiles" failed with the following error: "Cannot find the object "##tempProcessFiles" because it does not exist or you do not have permissions.". Possible failure reasons: Problems with the query, "ResultSet" property not set correctly, parameters not set correctly, or connection not established correctly.

Running this package in debug mode does not recreate this scenario. Everything works fine.

I discovered (after many days of frustration, chasing ideas that sent me in circles) that by removing the GO statement in 'Create Temp Table' my package would execute normally.

It was determined that there were no errors or no accidental dropping of my temp table. Plus, I had persist security info set to false like always, delay validation set to true like always; but my drop temp table task wasn't firing - I even tried deploying it with it disabled. None of my other packages used this global temp table and the database had no scheduled jobs or triggers dropping it or anything ridiculous like that.

All I can determine is that the GO operator here was causing my session to the database to terminate and cause my temp table to be dropped immediately. Is this how GO operators works in SSIS? If I were to run a script on SQL Server using the exact same syntax as I have in my package, I definitely would not experience this kind of thing, so it's thrown me for a loop. But I'm not a DBA, so it's probably something fundamental or subtle to that area of work.

Can anyone explain what really happened here? Or would I need to provide more detail about my package to get a sufficient answer? The only change I did was removing GO from 'Create Temp Table', so that was the definite fix.

Answer 1

It seems that the connection is being dropped after all, despite RetainSameConnection . To gather more information, try following:

Run a trace while executing the package to confirm the above (add Security Audit > Login/Logout and Sessions > Existing connections). Pay attention to StartTime and EndTime, maybe it'll be something interesting like 30s (default command timeout)?

Then try running this package with Crate and Truncate tasks only (without the loop) to eliminate a possibility that other components are interfering (Data Sources using same Connection Manager?). If it works, try it with a loop, but with Truncate task only placed inside, and keep adding other components.