How does one make NHibernate stop using nvarchar(4000) for insert parameter strings?

Question

I need to optimize a query that is being produced by a save (insert query) on a domain entity. I\'ve configured NHibernate using Fluent NHibernate.

Here\'s the query ge

Answer 1

Okay this is what we have to do, the SQLClientDriver ignores the length property of the SqlType. So we created a our own driverclass inheriting from SQLClientDriver and override the method GenerateCommand...Something like this:

public override IDbCommand GenerateCommand(CommandType type, NHibernate.SqlCommand.SqlString sqlString, SqlType[] parameterTypes)
{
    var dbCommand = base.GenerateCommand(type, sqlString, parameterTypes);
    SetParameterSizes(dbCommand.Parameters, parameterTypes);
    return dbCommand;
}

private static void SetParameterSizes(IDataParameterCollection parameters, SqlType[] parameterTypes)
{
    for (int index = 0; index < parameters.Count; ++index)
        SetVariableLengthParameterSize((IDbDataParameter)parameters[index], parameterTypes[index]);
}

private static void SetVariableLengthParameterSize(IDbDataParameter dbParam, SqlType sqlType)
{
    SetDefaultParameterSize(dbParam, sqlType);
    if (sqlType.LengthDefined && !IsText(dbParam, sqlType) && !IsBlob(dbParam, sqlType))
        dbParam.Size = sqlType.Length;
    if (!sqlType.PrecisionDefined)
        return;
    dbParam.Precision = sqlType.Precision;
    dbParam.Scale = sqlType.Scale;
}