之前曾有一篇POST是关于用CTE实现Split，这种方法已经比传统的方法高效了。今天我们就这个方法与CLR实现的Split做比较。在CLR实现Split函数的确很简单，dotnet framework本身就有这个function了。

1: /// 
 
/// SQLs the array. 
/// 
 
/// The STR. 
/// The delimiter. 
///  
/// 1/8/2010 2:41 PM author: v-pliu 
[SqlFunction(Name = "CLR_Split", 
FillRowMethodName = "FillRow", 
TableDefinition = "id nvarchar(10)")] 
public static IEnumerable SqlArray(SqlString str, SqlChars delimiter) 
{ 
if (delimiter.Length == 0) 
return new string[1] { str.Value }; 
return str.Value.Split(delimiter[0]); 
} 
/// 
 
/// Fills the row. 
/// 
 
/// The row. 
/// The STR. 
/// 1/8/2010 2:41 PM author: v-pliu 
public static void FillRow(object row, out SqlString str) 
{ 
str = new SqlString((string)row); 
} 
 
然后Bulid,Deploy一切OK后，在SSMS中执行以下测试T-sql: 
 代码如下:

DECLARE @array VARCHAR(max) 
SET @array = '39,15,93,68,,43,90,58,39,9,26,26,,47,91,57,98,16,55,9,63,29,69,16,41,76,34,60,68,,61,53,32,30,11,72,57,63,36,43,22,14,60,38,24,5,66,26,26,21,22,99,55,18,7,10,46,76,27,88,9,29,,75,48,72,94,59,35,19,0,35,79,11,87,49,68,30,91,35,9,7,34,47,41,61,98,13,22,1,26,80,35,48,34,92,24,85,90,51' SELECT id FROM dbo.CLR_Split(@array,',') 
 

我们来看它的Client Statistic:

接着我们执行测试T-sql使用相同的array:
 代码如下:

DECLARE @array VARCHAR(max) 
SET @array = '39,15,93,68,,43,90,58,39,9,26,26,,47,91,57,98,16,55,9,63,29,69,16,41,76,34,60,68,,61,53,32,30,11,72,57,63,36,43,22,14,60,38,24,5,66,26,26,21,22,99,55,18,7,10,46,76,27,88,9,29,,75,48,72,94,59,35,19,0,35,79,11,87,49,68,30,91,35,9,7,34,47,41,61,98,13,22,1,26,80,35,48,34,92,24,85,90,51' 
SELECT item FROM strToTable(@array,',') 


CTE实现的Split function的Client statistic:

通过对比，你可以发现CLR的performance略高于CTE方式，原因在于CLR方式有Cache功能，并且把一个复杂的运算放到程序里比DataBase里更加高效。
您还可以参考：

Author:Petter Liu 




下载本文