internal static Dictionary <DateTime, SoaRowsRepo1> CreateMemoryBasedIndex(this MonthShardPassbookDB monthDb, int dictLength = 10)
        {
            var dict     = new Dictionary <DateTime, SoaRowsRepo1>();
            var monthNow = DateTime.Now.MonthFirstDay();

            for (int i = 0; i < dictLength; i++)
            {
                var repo = monthDb.CreateInMemoryShard();
                dict.Add(monthNow.AddMonths(i * -1), repo);
            }
            return(dict);
        }