问NpgSqlCopyIn推荐的错误处理

EN

try
{
var items = GetSourceData(task);
connection.Open();
var command = new NpgsqlCommand(null, connection);

BeforeDestinationCommandExecution(task, command);

command.CommandText = string.Format("COPY {0} FROM STDIN", task.DestinationTable);
command.CommandTimeout = 3600;
var cin = new NpgsqlCopyIn(command, connection);
var rowCount = 0;

try
{
    cin.Start();
    foreach (var item in items)
    {
        var b = StreamEncoding.GetBytes(ConvertSourceData(item));
        cin.CopyStream.Write(b, 0, b.Length);
        ++rowCount;
    }
    cin.End();
    log.Debug(string.Format("Table {0} contained {1:N0} records", task.DestinationTable, rowCount));
}
catch (Exception e)
{
    log.ErrorException("Exception caught in inner try block - MigrateWithCopyMode", e);
    try
    {
        // send CopyFail to server
        cin.Cancel("Undo copy");
    }
    catch (Exception cancelException)
    {
        // we should get an error in response to our cancel request:
        if (!cancelException.ToString().Contains("Undo copy"))
        {
            throw new Exception("Failed to cancel COPY: " + cancelException + " upon failure: " + e);
        }
    }
    throw;
}
finally
{
    _migrationCounts.Add(task.DestinationTable, rowCount);
}

Error [16] [HubAdapterMsSqlPostgres] Unhandled exception Npgsql.NpgsqlException:
null value in column "name_ru" violates not-null constraint
Severity: ERROR
Code: 23502
   at Npgsql.NpgsqlState.<ProcessBackendResponses_Ver_3>d__a.MoveNext()
   at Npgsql.NpgsqlState.IterateThroughAllResponses(IEnumerable`1 ienum)
   at Npgsql.NpgsqlConnector.NpgsqlContextHolder.ProcessServerMessages()
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()