Intermittent Slow SQL Connection

[wijb]

Hopefully somebody can help me with an issue that is driving me crazy!

I have recently built a new version of a .NET application I created last year as our SQL Server address had changed IP. The application is built in VB using Visual Studio 2005.

I reinstalled the application on a mixture of Desktop machines and Laptops (all running XP SP3) however when the application tries to connect to the SQL Server on the laptops you can see a noticable difference in speed, usually around 2-3 seconds delay.

I have checked and double checked all the Network adaptor settings however nothing is showing out of the ordinary. I have also reinstalled the application to hope this would work but still just as slow.

I am using SQL Server Express 2008 using two connection methods (ODBC and ADO).

Any help or suggestions would be really appreciated! Thanks.

 

[SQLScholar]

Is the SQL server running on a different version of windows now?

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http://www.fountain.me.uk

Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind - Bernard Baruch

Computer Science is no more about computers than astronomy is about telescopes - EW Dijkstra
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[wijb]

Thanks for your reply SQLScholar!

No the SQL server is the same config as before. The desktop machines connect fine and the performance is fantastic it is just the laptops that are having the 'slowness'.

I have ruled out network issues as I plugged one of the laptops into the same network cable that a desktop was using fine - the slowness still happened :-(

 

[SQLScholar]

OK.

Well - lets rule things out.

It doesnt seem to be the SQL box - or all will have trouble connecting. It doesnt care its a laptop!

So - whats different with the laptops?

Is there any difference in network config between the laptops and desktops? Different domain, different controller, static\DHPC address?

I am no network guy - can you measure network throughput? It might be a question for a different forum?

Actually..... was the speed for laptops ok before or is this a new thing?

Dan

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http://www.fountain.me.uk

Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind - Bernard Baruch

Computer Science is no more about computers than astronomy is about telescopes - EW Dijkstra
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[wijb]

I have checked the network settings on both the desktops and laptops and there is no visible difference that I can see in settings. All machines are on the same domain, same controller and are all on the same network subnet.

Could the issue be around a corrupt ADODB/ODBC driver on the laptops?

The laptops connected fine until the build of the new software was installed and then it went slow. The same build of application is installed on the desktops though and there are no config settings in the coding that would change depending on the machine type...


Jamie

 

[SQLScholar]

Doubt it - plus unless you have rebuilt the laptops, all with the same image since server move its very unlikely.

Is there windows firewall turned on at either end (server or client)?

Are all the clients (lappys and desktops) on the same version of windows? What version is it? If its windows 7 (or vista i think!) then take a look at this:

http://ttcshelbyville.wordpress.com/2009/11/30/slow-sql-connection-to-windows-7/

I have seen network card settings for IPv6 play hell with making connections slow (not in SQL) and apparently they can cause SQL problems too.

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

http://www.fountain.me.uk

Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind - Bernard Baruch

Computer Science is no more about computers than astronomy is about telescopes - EW Dijkstra
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[wijb]

Thanks for the response Dan.

I managed to resolve the issue. It appears that the built-in ODBC drivers for SQL that I was referencing to in my connection strings have become 'unstable' and were delaying sending the network packets through to the server.

The SQL server was responding as soon as the packets were received but it was the laptops themselves that were not sending the packets for 2-3 seconds after the command had been clicked. I will try investigate why this happened only on the laptops at the same time though (maybe a group policy update/SMS update etc...).

I fixed the issue by installing the SQL Native Client 2008 Feature Pack (April 2009) from Microsoft. Changed the connection string to reference SQLNCLI10 instead of SQLOLEDB and it works a treat! It actually works faster than it did before any of this happened.

Cheers for your help! Much Appreciated.


Jamie