I'm having huge difficulty debugging database operations from Silverlight RIA. This is understandable, I suppose, since database operations are abstracted by about 3 layers of services and ORM and stuff, but is there any way I can see what the database is telling me regarding the issue? I'm able to find an EntityConflict object which doesn't offer much information.
The only field which seems to indicate any problem is "IsDeleted" property equal to true, however this property is not well documented at MSDN and I cannot even be sure that having it be true is an issue.
I've attempted to use fiddler, however no errors are reaching that, I've attached to the application's unhadled exception, but that points me back to EntityConflict, which I am recovering through handling SubmittedChanges event and accessing the args. I've even enabled WCF tracing to attempt to recover some information but, of course, nothing there either.
Did you inspect SubmitOperation.Error after the submit operation failed? It should contain the error information you seek. More information on error handling can be found here: Link
The issue was a known issue, at least a few years ago, where INSTEAD OF INSERT doesn't return Scope_identity for a column inserted by this method. EF uses this value to verify that an insert was completed. When it fails, you get a deletion conflict. This is, apparently, a known issue with the SQL Server EF provider, however I have been unable to confirm that it's been resolved.
Related
I am getting the error: Pipe Notifications bind failure "Bucket already bound from another Snowflake account"
We have 2 accounts, so I removed the bucket references from one account, but I am still getting this error. I have an S3 Integration setup.
Do I need to re-do the integration to get this working properly? I am unable to create additional / new transforms on this pipe.
Does this require Snowflake hands to fix?
Thanks!
Someone (bstora) answered this yesterday with a correct answer, I'm not sure why it's been deleted, but it was 100% correct.
So, to rewrite what they wrote, if this happens to you then you will need to reach out to Snowflake Support to have them determine the correct course of action. There is currently no action you can take as a user to correct or fix this.
This page will show you how to create a support ticket, if you haven't created one in the past.
https://community.snowflake.com/s/article/How-To-Submit-a-Support-Case-in-Snowflake-Lodge
On the data side:
I have a table.
This table has a number of fields.
And this table has been added an index that is unique. The intention of this index was to not allow the insertion of Duplicate values.
The table has been manually tested and it complies with that functionality. That is, it works for the purpose intended. The table does not accept duplicate values, and every row entered is unique.
On the Telerik Kendo side:
In my application, I have set up the ORM Open Access UI grid profiler. I know that the SQL statement throws an error when I insert duplicate values because I have tested it and read it.
However, when I insert the duplicate value via the application, with the ORM Open Access window enabled in order to visualize it, the profiler DOES NOT catch it.
There is no error message.
I have tried every piece of advice that I have read in this forum in order to make the Open Access catch the error, but nothing has worked.
My question is: how can I make the ORM Open Access profiler catch the error that is being generated by the SQL statement every time I insert a duplicate value?
I know this question will be useful to other users who may be facing the same struggles.
Thanks in advance for sharing your knowledge and providing your guidance.
I am using Telerik OpenAccess ORM and I never had this issue. I just tested it again with the last version of OpenAccess ORM and OpenAccess Profiler, and the exception was caught and shown. In the options of the Profiler, there is an Alert rule for Runtime Exception, lest you uncheck this rule? If the rule is not checked the runtime exceptions will not be shown.
If this is not the case, I would recommend you to write about your issue in Telerik Forums or to contact their Support team. There you will receive more help.
We have built a website based on the design of the Kigg project on CodePlex:
http://kigg.codeplex.com/releases/view/28200
Basically, the code uses the repository pattern, with a repository implementation based on Linq-To-Sql. Full source code can be found at the link above.
The site has been running for some time now and just about a year ago we started to get errors like:
There is already an open DataReader associated with this Command which must be closed first.
ExecuteNonQuery requires an open and available Connection. The connection's current state is closed.
These are the closest error examples I can find based on my memory. These errors started to occur when the site traffic started to pick up. After banging my head against the wall, I figured out assumed that the problem is inherit within Linq-To-Sql and how we are using the same connection to call multiple commands in a single web request.
Evenually, I discovered MARS (Multiple Active Result Sets) and added that to the data context's connection string and like magic, all of my errors went away.
Now, fast forward about 1 year and the site traffic has increased tremendously. Every week or so, I will get an error in SQL Server that reads:
A severe error occurred on the current command. The results, if any, should be discarded
Immediately after this error, I receive hundreds to thousands of InvalidCastException errors in the error logs. Basically, this error shows up for each and every call to the Linq-To-Sql data context. Only after I restart the web server do these errors clear up.
I read a post on the Micosoft Support site that descrived my problem (minus the InvalidCastException errors) and stating the solution is that if I'm going to use MARS that I should also use Asncronous Processing=True. I tried this, but it did not solve my problem either.
Not really sure where to go from here. Hopefully someone here has seen and solved this problem before.
I have the same issue. Once the errors start, I have to restart the IIS Application Pool to fix.
I have not been able to reproduce the bug in dev despite trying many different scenarios involving multi-threading, leaving connections open, etc etc.
One possible lead I do have is that amongst the errors in the server Event Log is an OutOfMemoryException for the Application Pool. Perhaps this is the underlying cause of the spurious SQL Datareader errors (a memory leak elsewhere). Although again I haven't been able to reproduce this in dev.
Obviously if you are using a 64 bit OS then this is probably not the cause in your case.
So after much refactoring and re-architecting, we figured out that problem all along is MARS (Multiple Active Result Sets) itself. Not sure why or what happens exactly but MARS somehow gets result sets mixed up and doesn't recover until the web app is restarted.
We removed MARS and the errors stopped.
If I remember correctly, we added MARS to solve the problem where a connection/command was already closed using LinqToSql and we tried to access an object graph that hadn't been loaded. Without MARS, we'd get an error. But when we added MARS, it seemed to not care about it. This is really a great example of us not really understanding what the heck we were doing and we learned some valuable (and expensive) lessons from this.
Hope this helps others who have experienced this.
Thanks to all how have contributed their comments and answers.
I understand you figured out the solution..
Following is not a direct solution to the problem; but it is good for others to take a look at
What does "A severe error occurred on the current command. The results, if any, should be discarded." SQL Azure error mean?
http://social.msdn.microsoft.com/Forums/en-US/bbe589f8-e0eb-402e-b374-dbc74a089afc/severe-error-in-current-command-during-datareaderread
I'm facing an extremely weird bug here and I'm not really sure If I'm following the right path to solving it or even how to solve it.
Here is the problem I'm facing: I start debugging a WPF application which uses log4net, NHibernate and LINQ to NHibernate, and when I try to get an Entity from the database my application and sometimes VS hang for a lot of time, and after a while an exception dialog opens showing a message containing the following information on a ContextSwitchDeadlock MDA:
The CLR has been unable to transition from COM context 0x34fc1a0 to COM context 0x34fc258 for 60 seconds. The thread that owns the destination context/apartment is most likely either doing a non pumping wait or processing a very long running operation without pumping Windows messages. This situation generally has a negative performance impact and may even lead to the application becoming non responsive or memory usage accumulating continually over time. To avoid this
I copied the code files to a new project and deleted the old project to see If I could make this message disappear, thinking it had something to do with my configuration. I started adding few things at a time to see what was causing it, and when I included log4net configuration code the bug appeared again. First I included it through AssemblyInfo and later trough code configuration on application startup, and absolutely nothing changed at all :(
So, here are my findings:
It only happens when I'm using log4net.
It happens when NHibernate loads an Entity from database (lazy loading).
I don't know what might be the source of this bug. It only happens when debugging in Visual Studio. I've tried following the steps on the "Enabling and Disabling MDAs" section of the following page: http://msdn.microsoft.com/en-us/library/d21c150d.aspx, but that doesn't work either, VS still hangs and it's memory usage increases.
When I run the program normally none of this happens, so I'm pretty sure this is not a deadlock situation, as this question suggests: contextswitchdeadlock (I've also tried the solutions posted there).
Because of that, I've decided to disable log4net and enable it again when deploying my app.
I'm posting this question to find out if somebody else has faced this bug or if somebody has some suggestions on how to solve it. Finally, it might help somebody else facing this very same problem.
When using the DebugAppender all the entities in the databases are loaded and all its data written to the debug output. That was causing the ContextSwitchDeadlock MDA since it tookmore than 60 seconds to run.
Disabling the DebugAppender solved my problem.
Thanks to Mauricio Scheffer for the tip.
We are using ASP.NET MVC with LINQ to SQL. We added some features and tested them all to perfection on our QA box. We are using Windows Server 2003 and SQL Server 2005. So when we pushed out changes to the Live web server we also used Red Gate SQL Compare to push new database changes to the LIVE database. We tested again between the few of us, no problems. Time for bed.
The morning comes and users are starting to hit the app, and BOOM. We have no idea why this would happen as we have not been doing any new types of code things that we were not doing before. However we did notice that during the SQL Compare sync the names of all the foreign keys were different between the two databases, not the IDs in the tables, FK_AssetAsset_A0EB67 to FK_AssetAsset_B67EF8 (for example, don't remember the exact number of trailing mixed characters during the SQL Compare), we are not sure why but that is another variable in this problem.
Strangely once this was all pushed out we could then replicate the errors on QA, but not before everything was pushed to LIVE.
QA and LIVE databases are on the same SQL Server, but the apps are on different instances of Windows Server 2003.
Errors generated:
Index was outside the bounds of the array.
Invalid attempt to call FieldCount when reader is closed.
Server failed to resume the transaction.
There is already an open DataReader associated with this Command which must be closed first.
A transport-level error has occurred when sending the request to the server.
A transport-level error has occurred when receiving results from the server.
Invalid attempt to call Read when reader is closed.
Invalid attempt to call MetaData when reader is closed.
Count must be positive and count must refer to a location within the string/array/collection. Parameter name: count
ExecuteReader requires an open and available Connection. The connection's current state is connecting.
Any one have any idea what the heck could have happened?
EDIT: Since we were able to replicate the errors all of a sudden on QA, it might not be a user load issue... Needless to say we all feel really screwed here.
Concurrency always brings bugs out of the woodwork. I'd recommend you check for objects that could be shared among requests (such as static members and singletons) and refactor your code so that as little as possible is shared.
As far as specifics go, for the error "There is already an open DataReader associated with this Command which must be closed first," you may want to try adding MultipleActiveResultSets=True to your connection strings.
It sounds like you're crossing the streams a bit and trying to share DataContexts across requests. My suggestion would be to wire in a dependancy injection framework that creates a new instance of the dependancy for each request.
I use Castle's IoC and wire it into the controller factory so that when it sees a dependancy on a repository it creates a new instance of that repository for each request. If you go this route let me know and I can shoot you a few more resources.