獲取Cassendra中某個ColumnFamly所有的值

項目中需要獲取Cassendra中某個ColumnFamly所有的值，並且緩存起來。感謝Andy童鞋給了我很好的示例

代碼背景：

這個ColumnFamly是Super的，SuperColumn是Year，Key是ID，每一個SuperColumn下面存放着不同的數據，比如MSR， Name，UpdateTime之類的。但我們這裏只需要MSR，這個字段是整數，所以最終的示例代碼如下：

public static Dictionary<string, int> GetLastestMSROfAllSchools()
{
    //開始StartKey是空值
    string startKey = "";
    //最大每次返回的數據個數
    int maxReturnCount = 500;
    //最終的結果保存在這個字典裏，這個是需要被緩存起來的
    Dictionary<string, int> dictMSR = new Dictionary<string, int>();
    //獲取所有的數據
    GetLatestMSRFromCassandra(startKey, maxReturnCount, ref dictMSR);
    return dictMSR;
}

private static void GetLatestMSRFromCassandra(string startKey, int maxReturnCount, ref Dictionary<string, int> dictMSR)
{
    string lastKey = string.Empty;
    UTF8EncoderHelper utf8 = new UTF8EncoderHelper();
    ConnectionString connString = new ConnectionString(DataAccessLib.CassandraAccess.ConnectionStringKeys.HouseHistory);
    // Get MSR list in a given range.
    List<CassandraKeySlice> listMSR = CassandraClient.GetRangeSliceCommand(connString, MSRProcessor.MSRColumnFamily, null, 100, maxReturnCount, startKey);
    if(listMSR == null || listMSR.Count == 0)
	return;

    for (int i = 0; i < listMSR.Count; i++)
    {
	CassandraKeySlice cassandraKeySlice = listMSR[i];
	string ncesSchoolId = lastKey = utf8.FromByteArray(cassandraKeySlice.Key);
	// Order MSRs of a school by year descending. 根據SuperColumn排序
	List<CassandraColumnOrSuperColumn> listOrderedMSR = cassandraKeySlice.Columns.OrderByDescending(x => utf8.FromByteArray(x.SuperColumn.Name)).ToList();
	if(listOrderedMSR != null && listOrderedMSR.Count > 0)
	{
	    //找到最近一年的MSR Column，餅獲取它的值
	    CassandraColumn msrColumn = listOrderedMSR[0].SuperColumn.Columns.Find(x => utf8.FromByteArray(x.ColumnName) == MovotoSchoolRankSavedDataColumns.MSR);
	    if (msrColumn != null)
	    {
	        // 如果找到的話把它存到字典裏面
		int tempMSR = System.BitConverter.ToInt32(msrColumn.Value, 0);
		if (!dictMSR.ContainsKey(ncesSchoolId))
		    dictMSR.Add(ncesSchoolId, tempMSR);
	    }
	}
    }

    if(listMSR.Count < maxReturnCount)
	return;
    else
    {
	GetLatestMSRFromCassandra(lastKey, maxReturnCount, ref dictMSR);
    }
}