VARBINARY does NULL is not mapped correctly by default

[ValtsS]

VARBINARY seems to be a special case which does not work correctly:

2024-08-05 19:06:04.7033|INFO|Getting replication information for replication set Test
2024-08-05 19:06:07.3604|INFO|Replicating table [dbo].[test2]
2024-08-05 19:06:07.3604|INFO|Starting replication for replication set Test
2024-08-05 19:06:07.3604|INFO|Database Secondary 1 is at version 24994
2024-08-05 19:06:07.3771|INFO|Snapshot isolation is enabled in database Primary
2024-08-05 19:06:07.3771|INFO|Current version of database Primary is 24997
2024-08-05 19:06:07.4134|INFO|Minimum version of table [dbo].[test2] in database Primary is 24984
2024-08-05 19:06:07.4134|DEBUG|Retrieving changes for table [dbo].[test2]: select c.SYS_CHANGE_OPERATION, c.SYS_CHANGE_VERSION, c.SYS_CHANGE_CREATION_VERSION,
                        c.[id], t.[dat]
                        from CHANGETABLE (CHANGES [dbo].[test2], @0) c
                        left outer join [dbo].[test2] t on c.[id] = t.[id] order by coalesce(c.SYS_CHANGE_CREATION_VERSION, c.SYS_CHANGE_VERSION), c.SYS_CHANGE_OPERATION
2024-08-05 19:06:07.4314|INFO|Table [dbo].[test2] has 1 change
2024-08-05 19:06:07.4368|INFO|Replicating 1 change to destination Secondary 1
2024-08-05 19:06:07.4368|DEBUG|Replicating change #1 of 1 (Version 24997, CreationVersion 24997)
2024-08-05 19:06:07.4368|DEBUG|Executing insert: set IDENTITY_INSERT [dbo].[test2] ON; insert into [dbo].[test2] ([id], [dat]) values (@0, @1); set IDENTITY_INSERT [dbo].[test2] OFF (@0 = 4, @1 = )
2024-08-05 19:06:07.4540|ERROR|Error replicating changes to destination Secondary 1 System.Data.SqlClient.SqlException (0x80131904): Implicit conversion from data type nvarchar to varbinary(max) is not allowed. Use the CONVERT function to run this query.
   at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
   at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
   at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString)
   at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async, Int32 timeout, Task& task, Boolean asyncWrite, SqlDataReader ds)
   at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, Boolean sendToPipe, Int32 timeout, Boolean asyncWrite, String methodName)
   at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
   at NPoco.Database.ExecuteNonQueryHelper(DbCommand cmd)
   at NPoco.Database.Execute(String sql, CommandType commandType, Object[] args)
   at SyncChanges.Synchronizer.PerformChange(Database db, Change change) in R:\Projects\IF\Sync2\SyncChanges\SyncChanges\Synchronizer.cs:line 563
   at SyncChanges.Synchronizer.Replicate(DatabaseInfo source, IGrouping`2 destinations, IList`1 tables) in R:\Projects\IF\Sync2\SyncChanges\SyncChanges\Synchronizer.cs:line 349
ClientConnectionId:1e0c653d-c85e-4ced-88b6-eeaa8197277b
Error Number:257,State:3,Class:16 HelpLink.ProdName: Microsoft SQL Server;HelpLink.ProdVer: 14.00.3411;HelpLink.EvtSrc: MSSQLServer;HelpLink.EvtID: 257;HelpLink.BaseHelpUrl: https://go.microsoft.com/fwlink;HelpLink.LinkId: 20476
2024-08-05 19:06:07.4818|INFO|Finished replication with errors

To work around this - check which columns can be nullable and are varbinary (maybe there are some more types?) - then insert SqlBinary.Null

[codecov]

Codecov Report

Attention: Patch coverage is 83.33333% with 4 lines in your changes missing coverage. Please review.

Project coverage is 87.71%. Comparing base (c7a7b7c) to head (f9ba38c).

Files	Patch %	Lines
SyncChanges/DataReaderExtensions.cs	76.92%	2 Missing and 1 partial ⚠️
SyncChanges/Synchronizer.cs	90.90%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #232      +/-   ##
==========================================
- Coverage   87.98%   87.71%   -0.27%     
==========================================
  Files           8        9       +1     
  Lines         491      513      +22     
  Branches       68       74       +6     
==========================================
+ Hits          432      450      +18     
- Misses         48       50       +2     
- Partials       11       13       +2     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[mganss]

Thanks! Can you adjust the varbinary test here?

SyncChanges/SyncChanges.Tests/Tests.cs

Lines 199 to 245 in c7a7b7c

	[Test]
	public void VarBinaryTest()
	{
	try
	{
	static void CreateUsersTable(string dbName)
	{
	using var db = GetDatabase(dbName);
	db.Execute(@"if not exists (select * from sys.tables where name = 'Users') create table Users (
	NUM_TRF int primary key not null,
	NAME varchar(255),
	DESCRIPTION varchar(1000),
	REPORT varbinary(max)
	)");
	db.Execute(@"alter table Users
	enable CHANGE_TRACKING
	with (TRACK_COLUMNS_UPDATED = OFF)");
	}
	DropTable("Users");
	CreateUsersTable(SourceDatabaseName);
	CreateUsersTable(DestinationDatabaseName);
	var sourceUser = new VarBinaryUser { Num_Trf = 1, Name = "Test", Description = "Test Description", Report = new byte[] { 1, 2, 3, 4 } };
	using (var db = GetDatabase(SourceDatabaseName))
	{
	db.Insert(sourceUser);
	sourceUser.Name = "Michael Jeffrey Jordan";
	db.Update(sourceUser);
	}
	var synchronizer = new Synchronizer(TestConfig);
	var success = synchronizer.Sync();
	Assert.That(success, Is.True);
	using (var db = GetDatabase(DestinationDatabaseName))
	{
	var user = db.Single<VarBinaryUser>("select * from Users");
	}
	}
	finally
	{
	DropTable("Users");
	}
	}

[ValtsS]

Later. I don't have any localdb sql server to test with. Could also add tests with transactions to see how they fail :-)

[mganss]

Do you know why the current test succeeds? What would need to be modified for it to fail?

[ValtsS]

It succeeds because varbinary(max) is not null. If you have a NULL value for it - it will fail.

[mganss]

Thanks. I'll fix the varbinary test. Would be great if you could add transaction tests later.