I'm having a helluva time wrapping a couple transactions to 2 different databases on the same SQL Server. I initially was having trouble with network DTC access and I resolved that. Now, the error that I continue to get is "Communication with the underlying transaction manager has failed."
We have some customer profiles in a database and when these profiles become outdated we want to move them to an 'archive' database for storage. The move is simply (italics for humor) adding them to the archive database and deleting them from the main/live database. I have a DataContext for each database. The code below performs the Add and then gets the error on the Delete when trying to use the second DataContext. I've only been working with LINQ for a few months and I've scoured articles for the past couple of days. I'd like to know if anything is wrong with my code or if there is still something not configured properly with the DTC or ???
We're running on VMware for my workstation and the server.
- Workstation is Windows 7 SP1
- Server is Windows and SQL Server 2008R2
Routine for the 'Move':
private int MoveProfileToArchiveDB( int iProfileId )
{
int rc = RC.UnknownError;
// get new Archive profile object
ProfileArchive.ProfileInfo piArchive = new ProfileArchive.ProfileInfo();
// 'Live' DataContext
using ( ProfileDataContext dbLive = new ProfileDataContext() )
{
// get Live profile
ProfileInfo piLive = ProfileInfo.GetProfile( dbLive, iProfileId );
// copy Live data to Archive profile object... including the id
ProfileArchive.ProfileInfo.CopyFromLive( piLive, piArchive, true );
}
bool bArchiveProfileExists = ProfileArchive.ProfileInfo.ProfileExists( piArchive.id );
// make the move a transaction...
using ( TransactionScope ts = new TransactionScope() )
{
// Add/Update to Archive db
using ( ProfileArchiveDataContext dbArchive = new ProfileArchiveDataContext() )
{
// if this profile already exists in the Archive db...
if ( bArchiveProfileExists )
{
// update the personal profile in Archive db
rc = ProfileArchive.ProfileInfo.UpdateProfile( dbArchive, piArchive );
}
else
{
// add this personal profile to the archive db
int iArchiveId = 0;
piArchive.ArchiveDate = DateTime.Now;
rc = ProfileArchive.ProfileInfo.AddProfile( dbArchive, piArchive, ref iArchiveId );
}
// if Add/Update was successful...
if ( rc == RC.Success )
{
// Delete from the Live db
using ( ProfileDataContext dbLive = new ProfileDataContext() )
{
// delete the personal profile from the Profile DB
rc = ProfileInfo.DeleteProfileExecCmd( dbLive, iProfileId ); // *** ERROR HERE ***
if ( rc == RC.Success )
{
// Transaction End (completed)
ts.Complete();
}
}
}
}
}
return rc;
}
NOTES:
I have a few different methods for the Delete and they all work outside the TransactionScope.
ProfileInfo is the main profile table and is roughly the same for both Live and Archive databases.
Any help is greatly appreciated! Thanks much...
Rather than continue criss cross comments, I decided to post this as an answer instead.
don't use error codes. That's what exceptions are for. The code flow is more difficult to read and error code returns invite to be ignored. Exceptions make the code easier to read and far less error prone.
If you use a TransactionScope, remember to always set the isolation level explicitly. See using new TransactionScope() Considered Harmful. The implicit isolation level of SERIALIZABLE is almost never called for and has tremendous negative scale impact.
Transaction escalation. Whenever multiple connections are opened inside a transaction scope they can escalate the transaction to a distributed transaction. The behavior differ from version to version, some have tried to document it, eg. TransactionScope: transaction escalation behavior:
SQL Server 2008 is much more intelligent then SQL Server 2005 and can
automatically detect if all the database connections in a certain
transaction point to the same physical database. If this is the case,
the transaction remains a local transaction and it is not escalated to
a distributed transaction. Unfortunately there are a few caveats:
If the open database connections are nested, the transaction is still
escalated to a distributed transaction.
If in the transaction, a
connection is made to another durable resource, the transaction is
immediately escalated to a distributed transaction.
Since your connection (from the two data contextes used) point to different databases, even on SQL Server 2008 your TransactionScope will escalate to a distributed transaction.
Enlisting your application into DTC is harmful in at least two ways:
throughput will sink through the floor. A database can support few thousand local transactions per second, but only tens (maybe low hundreds) of distributed transactions per second. Primarily this is because of the complexity of two phase commit.
DTC requires a coordinator: MSDTC. The [security enhancements made to MSDTC] make configuration more challenging and it certainly is unexpected for devs to discover that MSDTC is required in their app. The steps described in the article linked are probably what you're missing right now. For Windows Vista/Windows 7/Windows Server 2008/Windows Server 2008R2 the steps are described in MSDTC in Windows Vista and Windows Server 2008, in How to configure DTC on Windows 2008 and other similar articles.
Now if you fix MSDTC communication following the articles mentioned above, your code should be working, but I still believe this archiving should not occur in the client code running EF. There are far better tools, SSIS being a prime example. A nightly scheduled job running SSIS would transfer those unused profiles far more efficiently.
Related
I am trying to implement both DbContext (SQLDBContext & DB2Context) in single transaction but every time facing an issue related to DB2.
It works fine with SQL but throws error when trying to access DB2.
The exception is :
Error in DB2Entities getter.Communication with the underlying transaction manager has failed.
The MSDTC transaction manager was unable to pull the transaction from the source transaction manager due to communication problems. Possible causes are: a firewall is present and it doesn't have an exception for the MSDTC process, the two machines cannot find each other by their NetBIOS names, or the support for network transactions is not enabled for one of the two transaction managers. (Exception from HRESULT: 0x8004D02B)
Please help me to implement both the DB transactions under single Transaction OR
if one of them fails then both should rollback.
Code is like:
var option = new TransactionOptions
{
IsolationLevel = System.Transactions.IsolationLevel.ReadCommitted,
Timeout = TimeSpan.FromSeconds(60)
};
using (var scopeOuter = new TransactionScope(TransactionScopeOption.Required, option))
{
SQLDBContext.Table.AddSomething();
SQLDBContext.SaveChanges();
using (var scopeInner = new TransactionScope(TransactionScopeOption.Required, option))
{
DB2Context.Table.AddSomething();
DB2Context.SaveChanges();
scopeInner.Complete();
}
scopeOuter.Complete();
}
Thank you!
With DB2, you will have to enable XA Transactions for MSDTC. Since you are also using multiple databases, you may have to also enable Network DTC Access (see image below).
To change these settings open the Component Services management snap-in (Administrative Tools -> Component Services, or run comexp.msc). Then under Computers -> My Computer -> Distributed Transaction Coordinator, right click on "Local DTC" and hit properties. You will get the screen below.
Recently we had Informix upgraded 11.7 to 12.10. After this deleting functionality not working as expected. Here is example query we are using:
SET LOCK MODE TO WAIT TO 5;
BEGIN WORK;
DELETE FROM DOCUMENT WHERE DOCUMENT_ID = 1000;
COMMIT WORK;
Above query not deleting any records and in some cases tables getting locked.
But same worked without any issues before upgrade.
And another interesting observation is, below query working without any issues
-- (SET LOCK MODE not used here):
BEGIN WORK;
DELETE FROM DOCUMENT WHERE DOCUMENT_ID = 1000;
COMMIT WORK;
We are using IBM Data Server Client 10.5.3 to connect to then Informix server using C#.
I use 2 different dlls to connect to 2 database in my project . each dll has it's own DAL layer .
now in a page I need to insert a set of related data into these 2 databases . I want to use transaction to make sure data are inserted correctly . but as I just have access to public methods of Insert() of each assembly , not the ADO.net codes . how can I handle this situation ? is there anything like this in c# ?
beginTransaction(){
dll1.class.Insert(data);
dll2.className.Insert(relatedData);
....
}
You are looking for the TransactionScope class:
Makes a code block transactional.
Example usage:
using (var tx = new TransactionScope())
{
dll1.class.Insert(data);
dll2.className.Insert(relatedData);
tx.Complete(); // if not executed, transaction will rollback
}
As #Anders Abel commented, the servers running the databases involved in the transaction will need the MSDTC service to be running and configured correctly on both the DB servers and the client machines. The DTCPing utility is very helpful in this regard.
As Steve B commented, there is an assumption here that all the databases and the associated drivers support distributed transaction enlistment. Check your documentation...
Recently our QA team reported a very interesting bug in one of our applications. Our application is a C# .Net 3.5 SP1 based application interacting with a SQL Server 2005 Express Edition database.
By design the application is developed to detect database offline scenarios and if so to wait until the database is online (by retrying to connect in a timely manner) and once online, reconnect and resume functionality.
What our QA team did was, while the application is retrieving a bulk of data from the database, stop the database server, wait for a while and restart the database. Once the database restarts the application reconnects to the database without any issues but it started to continuously report the exception "Could not find prepared statement with handle x" (x is some number).
Our application is using prepared statements and it is already designed to call the Prepare() method again on all the SqlCommand objects when the application reconnects to the database. For example,
At application startup,
SqlCommand _commandA = connection.CreateCommand();
_commandA.CommandText = #"SELECT COMPANYNAME FROM TBCOMPANY WHERE ID = #ID";
_commandA.CommandType = CommandType.Text;
SqlParameter _paramA = _commandA.CreateParameter();
_paramA.ParameterName = "#ID";
_paramA.SqlDbType = SqlDbType.Int;
_paramA.Direction = ParameterDirection.Input;
_paramA.Size = 0;
_commandA.Parameters.Add(_paramA);
_commandA.Prepare();
After that we use ExceuteReader() on this _commandA with different #ID parameter values in each cycle of the application.
Once the application detects the database going offline and coming back online, upon reconnect to the database the application only executes,
_commandA.Prepare();
Two more strange things we noticed.
1. The above situation on happens with CommandType.Text type commands in the code. Our application also uses the same exact logic to invoke stored procedures but we never get this issue with stored procedures.
2. Up to now we were unable to reproduce this issue no matter how many different ways we try it in the Debug mode in Visual Studio.
Thanks in advance..
I think with almost 3 days of asking the question and close to 20 views of the question and 1 answer, I have to conclude that this is not a scenario that we can handle in the way we have tried with SQL server.
The best way to mitigate this issue in your application is to re-create the SqlCommand object instance again once the application detects that the database is online.
We did the change in our application and our QA team is happy about this modification since it provided the best (or maybe the only) fix for the issue they reported.
A final thanks to everyone who viewed and answered the question.
The server caches the query plan when you call 'command.Prepare'. The error indicates that it cannot find this cached query plan when you invoke 'Prepare' again. Try creating a new 'SqlCommand' instance and invoking the query on it. I've experienced this exception before and it fixes itself when the server refreshes the cache. I doubt there is anything that can be done programmatically on the client side, to fix this.
This is not necessarily related exactly to your problem but I'm posting this as I have spent a couple of days trying to fix the same error message in my application. We have a Java application using a C3P0 connection pool, JTDS driver, connecting to a SQL Server database.
We had disabled statement caching in our the C3P0 connection pool, but had not done this on the driver level. Adding maxStatements=0 to our connection URL stopped the driver caching statements, and fixed the error.
I have a problem, for saving a file and inserting a record in DB in a TransactionScope; Means saving file and inserting record, must depend together = or both or neither. Can anybody help me please?
Transactional NTFS
One of the coolest parts about
Transactional NTFS is that it can work
with a large number of other
transactional technologies. Because
TxF uses the new Kernel Transaction
Manager (KTM) features, and because
the new KTM can work directly with the
Microsoft® Distributed Transaction
Coordinator (DTC), any technology that
can work with DTC as a transaction
coordinator can use transacted file
operations within a single
transaction. This means that you can
now enlist transacted file operations
within the same transaction as SQL
operations, Web service calls via
WS-AtomicTransaction, Windows
Communication Foundation services via
the OleTransactionProtocol, or even
transacted MSMQ operations.
MSDN link
Alpha FS provides Transaction NTFS in .NET.
see Alphaleonis.Win32.Filesystem.KernelTransaction(Transaction transaction). You can get the current transaction by Transaction.Current
using (TransactionScope ts = new TransactionScope(TransactionScopeOption.RequiresNew))
{
//KernelTransaction is in AlphaFS
KernelTransaction kt = new KernelTransaction(Transaction.Current);
//Append "hello" to text file named "text.txt"
Alphaleonis.Win32.Filesystem.File.WriteAllText(kt, "text.txt", "hello");
//No text appended because exception will be thrown
throw new Exception("oops");
ts.Complete();
}
try
{
// Start DB Transaction
// Save To DAtabase code
// Save To File Code
// Commit DB Transaction
}
catch
{
// Rollback DB Transaction
}
Please notice Sequence of DB should be first then Saving to the file.