Sunday, September 23, 2007

UPDATE: SSIS - deadlock was detected while trying to lock variables

Recently I found this issue of deadlock variables in SSIS and finally made two solutions

1. Instead of declaring variables in Script properties (ReadOnlyVariables / ReadWriteVariables), better to make use of Dts.VariableDispenser.LockForRead / Dts.VariableDispenser.LockForWrite in the script to lock variables

2. I also solved my problem by running child packages out-of-proc (ExecuteOutOfProcess=TRUE in Execute Package Task), this is more to do with script caching

But recently I saw something strange and found out that one of my script is making use of this type of code and I am getting this error again.....

"The script threw an exception: A deadlock was detected while trying to lock variables "variable names (comma separated)" for read access and variables "variable names (comma separated)" for read/write access. A lock cannot be acquired after 16 attempts. The locks timed out."


Dim var As Variables






'Problem Line, Just remove the reference to Dts.Variables

Dts.Variables("User::VarName").Value = "SomeVal"


'Correct Line, make use of locally declared "var" Variable

var("User::VarName").Value = "SomeVal"




To solve the situation I made a quick fix and change my Dts.Variables to local variable collection I defined in the beginning "var".

As we can see in this script that we are locking one variable for write. But after using the GetVariables we MUST use "var" collection to write data and should NOT use Dts.Variables and that fixed my problem.

So I think this is some sort of double locking issue, like if I lock the variable using "Dts.VariableDispenser" and if I try to access the same variable again with Dts.Variables instead of "var" then SSIS tries to lock that again......


- Mohit Nayyar

Friday, September 14, 2007

SQL Query tool that generates HTML / PDF / Word / Excel output

I just saw this new query tool from SQL Answers.

The beauty of this tool is to directly generate the output of any query into PDF / HTML / Excel / Word / CSV format. Please take a look here…....

Mohit Nayyar SQL Query Tool

This seems to be a lightweight tool to query multiple databases platforms like Microsoft SQL Server, Oracle, DB2, Microsoft Access and MySQL, but I just tested this for Microsoft SQL Server 2005 and I am really happy with this.

This makes things really easy when you need to send the output in PDF or HTML without any extra effort.

On the similar lines Microsoft also offers a “SQL Server Web Data Administrator” tool, which is very useful because of its basic web interface. You can find this here…….

- Mohit Nayyar

Thursday, September 13, 2007

DTS to SSIS migration

Today I saw a new product coming soon to do DTS to SSIS migration called DtsXchange.

Looks promising and this is also capable to do something extra which built-in DTS migration doesn’t do like Dynamic Properties. Have a look here

Users can also migrate existing DTS packages into SSIS using the FREE migration wizard provided by SQL Server 2005 but this wizard doesn’t cover complete DTS package. So in some cases manual effort is required, and SSIS doesn’t support some of the DTS features, so the user has to manually implement the functionality in new SSIS package.

You can find some known issues in migration here

But on top of this SSIS allows you to run the existing DTS package even without any change, using a wrapper called “Execute DTS 2000 Package Task” in the new SSIS package.

So if you don’t have the bandwidth to migrate the existing package then keep on running the old DTS packages in SSIS and start making new packages in SSIS.

Obviously you will miss the “All NEW SSIS” but it’s an easy work around. But I think you will miss a lot, because SSIS is NOT a new name of DTS but it's a truly enterprise level ETL tool. So its always better to migrate to SSIS as soon as possible.

- Mohit Nayyar