private IOrderedQueryable<InvoiceForm> GetAllQuery()
{
    var feedOptions = new FeedOptions { MaxItemCount = -1 };
    var documentCollectionUri = new Uri(_dataContext.DocumentCollection.DocumentCollection.AltLink, UriKind.RelativeOrAbsolute);
    var query = _dataContext.Database.Client.CreateDocumentQuery<InvoiceForm>(documentCollectionUri, feedOptions);
    return query;
}