Cadenas largas en N-Hibernate con Oracle causan error

Este es un problema conocido con .NET proporcionado System.Data.OracleClient.OracleConnection conductor. La solución es usar el cliente ODP.net proporcionado por Oracle Oracle.DataAccess.Client.OracleConnection (consulte:http://nuget.org/packages/odp.net.x86/) o use la siguiente solución (referencia de:http://thebasilet.blogspot.be/2009/07/nhibernate-oracle-clobs.html ).

public class CustomOracleDriver : OracleClientDriver
{
    protected override void InitializeParameter(System.Data.IDbDataParameter dbParam, string name, SqlType sqlType)
    {
        base.InitializeParameter(dbParam, name, sqlType);


        // System.Data.OracleClient.dll driver generates an ORA-01461 exception because 
        // the driver mistakenly infers the column type of the string being saved, and 
        // tries forcing the server to update a LONG value into a CLOB/NCLOB column type. 
        // The reason for the incorrect behavior is even more obscure and only happens 
        // when all the following conditions are met.
        //   1.) IDbDataParameter.Value = (string whose length: 4000 > length > 2000 )
        //   2.) IDbDataParameter.DbType = DbType.String
        //   3.) DB Column is of type NCLOB/CLOB

        // The above is the default behavior for NHibernate.OracleClientDriver
        // So we use the built-in StringClobSqlType to tell the driver to use the NClob Oracle type
        // This will work for both NCLOB/CLOBs without issues.
        // Mapping file must be updated to use StringClob as the property type
        // See: http://thebasilet.blogspot.be/2009/07/nhibernate-oracle-clobs.html
        if ((sqlType is StringClobSqlType))
        {
            ((OracleParameter)dbParam).OracleType = OracleType.NClob;
        }
    }
}

Necesitas actualizar tu SessionFactory para usar este controlador, así como actualizar cualquiera de sus asignaciones de clob para usar StringClob tipo personalizado

Map(x => x.EventType).CustomSqlType("Clob").CustomType("StringClob");