private IEnumerable <KeyValuePair <string, string> > GetNotEqual()
        {
            var groups    = index.GetAll().ToList();
            var equalItem = groups.First(p => p.Key == filter.Value);

            groups.Remove(equalItem);

            foreach (var group in groups)
            {
                var groupKeys = group.Value.Split(new string[] { "###" }, StringSplitOptions.RemoveEmptyEntries);
                foreach (var key in groupKeys)
                {
                    yield return(new KeyValuePair <string, string>(key, repository.Get(databaseFile, table.Name, key)));
                }
            }
        }