Solving a timeout error for SQL query

Question

I am getting this error:

Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.

I know there are already guides out there to help solve this but they are not working for me. What am I missing or where should I add the code to these SQL statements in my C# program:

String sql = project1.Properties.Resources.myQueryData;

SqlDataAdapter sqlClearQuestDefects = new SqlDataAdapter(sql,
    "Data Source=ab;Initial Catalog=ac;User ID=ad; Password =aa");

DataSet lPlanViewData = new DataSet();
sqlClearQuestDefects.Fill(lPlanViewData, "PlanViewData");

I am getting the timeout error at this line:

SqlDataAdapter sqlClearQuestDefects = new SqlDataAdapter(sql, 
    "Data Source=ab;Initial Catalog=ac;User ID=ad; Password =aa");

Answer 1

Since the exact command to increase connection time out wasn't mentioned in the other answers (of yet)- if you do determine a need to increase your connection time out, you would do so in your connection string as follows:

 Data Source=ab;Initial Catalog=ac;User ID=ad; Password =aa; Connection Timeout=120

Where 120 = 120 seconds. Default is 20 or 30 as I recall.

Answer 2

This is probably a connection issue with your database, for example if you had the following connection string:

"Data Source=MyDatabaseServer...

Then you need to make sure that:

• The machine MyDatabaseServer is connected to the network and is accessible from the machine you are running your application from (under the name "MyDatabaseServer")
• The database server is running on MyDatabaseServer
• The database server on MyDatabaseServer is configured to accept connections from remote machines
• The firewall settings both on the local machine and MyDatabaseServer are correctly set up to allow SQL Server connections through
• Your username / password etc... are correct

You can also try connecting to the given database instance using SQL Server Management Studio from the client machine as a diagnosis step.

There are plenty of articles that address SQL Server connectivity issues - do a Google search for the specific error message that comes up or failing that as a specific question on Server Fault

Answer 3

Faced this problem recently and found the resolution that worked for me.

By the way, setting Timeout = 0 helped to avoid the exception, but the execution time was unreasonable, while manual execution of the store procedure took a few seconds.

Bottom line: I added SET IMPLICIT_TRANSACTIONS OFF to the stored procedure that is used to fill the data set.

From MSDN:

The SQL Server Native Client OLE DB Provider for SQL Server and the SQL Server Native Client ODBC driver automatically set IMPLICIT_TRANSACTIONS to OFF when connecting. SET IMPLICIT_TRANSACTIONS defaults to OFF for connections with the SQLClient managed provider, and for SOAP requests received through HTTP endpoints. [...] When SET ANSI_DEFAULTS is ON, SET IMPLICIT_TRANSACTIONS is ON.

So I believe that in my case defaults weren't as required. (I couldn't check that. Don't have enough privileges on SQL server). But adding this line to my SP solved the problem.

IMPORTANT: In my case I didn't need the transaction, so I had no problem to cancel the implicit transaction setting. If in your case transaction is a must you, probably, shouldn't use this solution.

Answer 4

You're trying to connect to a SQL Server, and it is taking longer than ADO.NET is willing to wait.

Try connecting to the same server, using the same username and password, using SQL Server Management Studio. If you get the same error, there is either something wrong with your connection string, the server you specify is not running, or you can't get to the server across the network from where you are (maybe you're on a public IP address trying to get in to an internal server name). I can't think of a scenario in which you'd enter the exact same server and credentials into SSMS and connect, then do the same in ADO.NET and fail.

If you're on a slow network, you can try increasing the timeout value. However, if a connection is going to happen at all, it should happen pretty quickly.

Take a look at both your SQL Native Client settings, and the SQL Server settings on the server. There is a section for allowed protocols; SQL can connect using a variety of protocols. Usually, you want TCP/IP for a server on the network, and Named Pipes for a server running on your own computer.

EDIT FROM YOUR COMMENT: Oh, that's normal; happens all the time. From time to time on a TCP network, packets "collide", or are "lost" in transmission. It's a known weakness of packet-switching technologies, which is managed by the TCP protocol itself in most cases. One case in which it isn't easily detected is when the initial request for a connection is lost in the shuffle. In that case, the server doesn't know there was a request, and the client didn't know their request wasn't received. So, all the client can do is give up.

To make your program more robust, all you have to do is expect a failure or two, and simply re-try your request. Here's a basic algorithm to do that:

SqlDataAdapter sqlClearQuestDefects;

short retries = 0;
while(true)
{
    try
    {
       sqlClearQuestDefects = new SqlDataAdapter(sql, "Data Source=ab;Initial Catalog=ac;User ID=ad; Password =aa");
         break;
    }
    catch(Exception)
    {
       retries++;
         //will try a total of three times before giving up
       if(retries >2) throw;    
    }
}

Answer 5

SqlDataAdapter adp = new SqlDataAdapter();
adp.SelectCommand.CommandTimeout = 0;  // Set the Time out on the Command Object