Today we had a lot more activity than normal between our Ruby on Rails application and our remote legacy SQL Server 2005 database, and we started getting the error below intermittently. What is is? How can I prevent it (besides avoiding the situation, which we're working on)?
Error Message:
ActiveRecord::StatementInvalid: DBI::DatabaseError: 08S01 (20020) [unixODBC][FreeTDS][SQL Server]
Bad token from the server: Datastream processing out of sync: SELECT * FROM [marketing] WHERE ([marketing].[contact_id] = 832085)
You need to use some sort of connection pooling.
Windows itself (including Windows Server X) will only allow a certain number of socket connections to be created in a given time frame, even if you close them. All others will fail after that.
A connection pool will keep the same sockets open, avoiding the problem. Also, new connections are real slow.
This Microsoft article says:
Often caused by an abruptly terminated network connection, which causes a damaged Tabular Data Stream token to be read by the client.
Was the server network bound? I have no experience with SQL Server, but does it have a limit on the number of connections you can make?
Add the following to your script; the first statement you run:
SET NO_BROWSETABLE OFF
Related
In our production environment there are sometimes peaks of ORA-12599 errors the connection works otherwise.
The description is not quite clear to me.
Cause: The data received is not the same as the data sent.
Action:
Attempt the transaction again. If error persists, check (and correct)
the integrity of your physical connection.
https://www.oraexcel.com/database-oracle-11gR2-ORA-12599
Does that mean there is a problem with my network cable? Or any other Hardware?
Because our DBA said the error can be caused by a configuration issue on the client side.
Edit:
It started without any changes on the client or server side. And there are spikes. 80 errors in an hour and then no errors for 4 hours while the load is more or less constant
It can mean a mismatch in how the client and the server are wishing to communicate (in encrypted fashion). For example, trying to connect to an 11g database with 10g JDBC drivers will get this because the encryption implementation changed between these versions.
Check your local (ie, client) sqlnet.ora file - you may need to opt for a different method or change the order of them.
The error can be typically be ignored (its informational) but using the latest drivers will normally resolve the issue.
We had sporadic ORA-12599 errors and also ORA-24300 ("bad value for mode") in a Python web app using Flask and uwsgi. It turned out to be caused by multiple worker processes writing and reading to/from the same TCP connection to the DB, giving chaotic communications on the socket.
In our setup this was caused by creating the TCP connections to the DB before uwsgi forked the workers, and the file descriptors being inherited. We fixed this by using uwgsi's lazy-apps mode.
See also this question.
I've just installed SlashDB and connected to an Azure SQL DB successfully. Querying works and everything is fine. However, after a while, if I retry my previously working query, I get an error from SlashDB:
500 Internal Server Error (pyodbc.OperationalError) ('08S01', u'[08S01] [FreeTDS][SQL Server]Write to the server failed (20006) (SQLExecDirectW)')
I'm not writing anything to the server, if that matters. But if I retry the query immediately, it works. My deep analysis (=guess) of this all is that the SQL Server terminates the idle connection. Now, I'd like SlashDB to retry when it fails, instead of returning error to the the client. Is this possible?
Apparently Azure SQL DB could be breaking connections due to either their redundancy limitations or the 30 minute idle.
https://azure.microsoft.com/en-us/blog/connections-and-sql-azure/
For performance reasons SlashDB does not establish a new connection for every request, but instead maintains a pool of connections.
MySQL, has a similar behavior, which is widely known (60 minutes idle timeout) and SlashDB actually has a logic to attempt reconnect. It should implement the same for all database types, but I need to confirm that with the development team (and fix if not the case).
In the meantime, you could either retry on the client side or send a periodic request for to avoid the timeout.
i am using sql server 2012 with desktop application as client , the application get errors after period of time when no activity on it , i googled about this issue all solutions points me to AUTO_CLOSE option on database but it's already set to false .
i thing is something missing in connection string (ADO Extension)
To be honest, if you have long running connections, you can hit these errors regardless due to firewalls / routers closing connections, etc. The correct solution is to instantiate a connection when you need it, use the connection and release it. With connection pooling, this is not really a performance problem.
If your long-running application is "bursty", it is sometimes convenient to open the connection, do a number of commands -- then when you go idle, release the connection and wait the next burst of activity.
We are running a website on a vps server with sql server 2008 x64 r2. We are being bombarded with 17886 errors - namely:
The server will drop the connection, because the client driver has
sent multiple requests while the session is in single-user mode. This
error occurs when a client sends a request to reset the connection
while there are batches still running in the session, or when the
client sends a request while the session is resetting a connection.
Please contact the client driver vendor.
This causes sql statements to return corrupt results. I have tried pretty much all of the suggestions I have found on the net, including:
with mars, and without.
with pooling and without
with async=true and without
we only have one database and it is absolutely multi-user.
Everything has been installed recently so it is up to date. They may be correlated with high cpu (though not exclusively according to the monitors I have seen). Also correlated with high request rates from search engines. However, high cpu/requests shouldn't cause sql connections to reset - at worst we should have high response times or iis refusing to send response.
Any suggestions? I am only a developer not dba - do i need a dba to solve this problem?
Not sure but some of your queries might cause deadlocks on the server.
At the point you detect this error again
Open Management Studio (on the server, install it if necessary)
Open a new query window
Run sp_who2
Check the blkby column which is short for Blocked By. If there is any data in that column you have a deadlock problem (Normally it should be like the screenshot I attached, completely empty).
If you have a deadlock then we can continue with next steps. But right now please check that.
To fix the error above, ”MultipleActiveResultSets=True” needs to be added to the connection string.
via Event ID 17886 MSSQLServer – The server will drop the connection
I would create an eventlog task to email you whenever 17886 is thrown. Then go immediately to the db and execute the sp_who2, get the blkby spid and run a dbcc inputbuffer. Hopefully the eventinfo will give you something a bit more tangible to go on.
sp_who2
DBCC INPUTBUFFER(62)
GO
Use a "Instance Per Request" strategy in your DI-instantiation code and your problem will be solved
Most probably you are using dependency injection. During web development you have to take into account the possibility of concurrent requests. Therefor you have to make sure every request gets new instances during DI, otherwise you will get into concurrency issues. Don't be cheap by using ".SingleInstance" for services and contexts.
Enabling MARS will probably decrease the number of errors, but the errors that are encountered will be less clear. Enabling MARS is always never the solution, do not use this unless you know what you're doing.
We have a very strange intermittent issue which has started coming up over the last month or so whereby some connections to mssql server fail with the error:
System.Data.SqlClient.SqlException: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)
The error does not bring down the site, nor does it require a db restart - if you simply rerun the same query will work the second time. This means a lot of users will hit an error every now and then and have to refresh the error page for things to work.
Now, my initial knee-jerk reaction was this could be due to:
Resource related issue - so I started running SQL profiler and perfmon, but did not find any issues with the serve struggling to keep up with the number of connections / sec. I've been looking at MSSQL:SQL Errors, MSSQL:Wait Statistics, MSSQL:Exec Statistics, MSSQL:Locks. Does anyone have any guidance on other stats I should be poking and prodding here?
Unclosed DB connections - I ruled this one out after going through all the data-tier code. We have all the fail safes in place to stop this from happening.
Connection / Network related issue: our SQL server sits on a separate server (MS SQL Server Standard 2008) to our application server (running ASP.Net on IIS7) - both servers run on xlarge Amazon EC2 instances with all security policies configured (as per Amazons direction). Anyone got guidance on how to test the connectivity between the two servers or if this could be the issue?
Is it a possible issue with the IIS connection string? I have not tested this but should we be fully qualifying the server with the computer name we are connecting to (just thought of it)? We use a connection string in the format: server=xxxxx;Database=xxxx;uid=xxxx;password=xxx;
Your thoughts and insight is very much appreciated!
Thanks in advance
Solved. After testing almost every possible performance metric and examining every piece of code, I discovered that the error was caused by a bit of deprecated database code. The main issue was being caused by code using:
SqlConnection.ClearPools;
For future reference, any other developers looking to debug their code and manage connection pools, an excellent resource can be found here: http://www.codeproject.com/KB/dotnet/ADONET_ConnectionPooling.aspx
Try changing the connection string to the FQDN+port
server=xxxxx.domain.tld,1234;
Note: you don't need any instance name if you use port
On our global corporate intranet... we had a similar issue that happened to remote clients: more often if they were further away, never in the same building as the server.
After some poking around, chatting to the DBAs and MS, it was said to be caused by timing/Kerberos/too many firewalls etc. Adding FQDN+port removed all our issues.
It may be solved by switching to TCP/IP instead of Named Pipes, if you can.
Perhaps you can test this by changing the server name to the server IP address.
I use server=tcp:servername in my connection string to force TCP.
KB313295
It seems like connection are not being closed correctly, and after some time you can't open any more new connections. As the total allowed connections to database is a constant digit.
If you are using C#/VB.net
Are you using "Using" statements to open the connections ?
using (System.Data.SqlClient.SqlConnection con = new SqlConnection("YourConnection string"))
{
con.Open();
}