July 22, 2015 at 2:14 am
I have an intermittent issue where some remote PC's occasionally fail to execute select queries that have a join or return multiple result sets, however simple one table select queries continue to work okay. When it does happen the PC's needs to be rebooted to get to work again. This may only happen some PC's while others continue to work away okay. I am using a VB6 application and ADO to connect to the database and the error message I get is a General Network Error, Server Not Found when it fails to execute the query. I have ran SQL Profiler on the server and while simple select queries continue to run away okay, a query a join does not even seem to show up in the profiler. The program has been working fine for 15 years with 1000's of users and has only now become an issue on one site for a number of users. Have tried moving the database to a different server and swapping network cards on the local PC's but can't seem to find the cause. The processor and the memory don't seem to be under load, but I am not sure if there is something else in SQL that is causing it to hang under certain conditions.
There have been network analysts experts in to run scans on the network, but I have not had the results of this back yet. Other applications do not seem to be affected so if this analysis does not show up anything, I am stumped.
Anyone any ideas or came across anything this before?
July 22, 2015 at 5:21 am
We need a bit more information than "fail to execute". When it fails, does it always fail with the "General Network Error, Server Not Found" error? Are there other errors? Does it appear to be spinning its wheels?
You say you're running these queries through a VB6 application. Are you executing them as stored procedures or straight T-SQL queries?
Is the end user running the query itself or using a form which calls the query?
Can you install SSMS tools on these remote machines and run the query from there with or without errors?
Does your application allow for real error handling or does it default to the above error because it doesn't know how to handle the response from SQL Server?
Honestly, VB6 is way out of date and might itself be the issue. I don't think it plays well with SQL 2008.
July 22, 2015 at 6:00 am
We need a bit more information than "fail to execute". When it fails, does it always fail with the "General Network Error, Server Not Found" error? Are there other errors? Does it appear to be spinning its wheels?
It always fails with Message: "[DBNETLIB][ConnectionRead (recv()).] General Network Error" Code: -2147467259. Yes it appears to spin wheels or timing out and hanging for a few seconds before giving this message.
You say you're running these queries through a VB6 application. Are you executing them as stored procedures or straight T-SQL queries?
Is the end user running the query itself or using a form which calls the query?
The queries are being ran from a search form where the user enters some search criteria and in turn a dynamic TSQL query is generated by the program. Have looked at the TQL generated and all looks standard.
Does your application allow for real error handling or does it default to the above error because it doesn't know how to handle the response from SQL Server?
The application reports whatever error is thrown by ADO
Honestly, VB6 is way out of date and might itself be the issue. I don't think it plays well with SQL 2008.
The application has been running for 15 years on 1000's of PC's up as far as Windows 8 and SQL 2014 with no issues so I don't think it is VB6. This issue is only actually related to one site with SQL 2008 R2, and is only for queries that contain a join. I can't understand why single table queries run fine, but query joins fail, and it is intermittent. A PC restart usually clears the issue, but it is not limited to one PC on the site, so it is not PC specific.
Can you install SSMS tools on these remote machines and run the query from there with or without errors?
This is the odd part. When the intermittent issue occurs, I cannot even connect using SQL Management Studio, but I can continue to run simple single table queries through ADO.
I have ran SQL Profiler on the server and I can see the simple queries hitting the server, but intermittently when the issue does occur, the queries with a join don't even appear in the profiler. It's as if they don't get the length of the server or are being off loaded by the server when it gets them, or refuses to run them.
July 22, 2015 at 7:13 am
Have you read this?
July 23, 2015 at 4:40 am
Luis Cazares (7/22/2015)
Have you read this?
Luis, I keep forgetting about that damn chimney. It can cause issues, can't it?
OP, you should definitely read this article. If nothing else, it can give you another place to start troubleshooting.
July 23, 2015 at 7:22 am
Brandie Tarvin (7/23/2015)
Luis Cazares (7/22/2015)
Have you read this?Luis, I keep forgetting about that damn chimney. It can cause issues, can't it?
I haven't encountered this problem, but it came out from a simple Google search. Having the exact error makes troubleshooting (googling) much easier. 😉
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