SQLSERVER2008中CTE的Split与CLR的性能比较

     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。
    我们新建一个DataBase project，然后建立一个UserDefinedFunctions,Code像这样:

    /// <summary>
    /// SQLs the array.
    /// </summary>
    /// <param name="str">The STR.</param>
    /// <param name="delimiter">The delimiter.</param>
    /// <returns></returns>
    /// 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]);
    }

    /// <summary>
    /// Fills the row.
    /// </summary>
    /// <param name="row">The row.</param>
    /// <param name="str">The STR.</param>
    /// 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:

DECLARE @array VARCHAR(max)
SET  @array = '39,15,93,68,64,43,90,58,39,9,26,26,89,47,91,57,98,16,55,9,63,29,69,16,41,76,34,60,68,64,61,53,32,30,11,72,57,63,36,43,22,14,60,38,24,5,66,26,26,21,22,99,55,18,7,10,46,76,27,88,9,29,89,75,48,72,94,59,35,19,0,35,79,11,87,49,68,30,91,35,9,7,34,47,41,61,98,13,22,1,26,80,35,48,34,92,24,85,90,51'
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:

DECLARE @array VARCHAR(max)
SET  @array = '39,15,93,68,64,43,90,58,39,9,26,26,89,47,91,57,98,16,55,9,63,29,69,16,41,76,34,60,68,64,61,53,32,30,11,72,57,63,36,43,22,14,60,38,24,5,66,26,26,21,22,99,55,18,7,10,46,76,27,88,9,29,89,75,48,72,94,59,35,19,0,35,79,11,87,49,68,30,91,35,9,7,34,47,41,61,98,13,22,1,26,80,35,48,34,92,24,85,90,51'
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：

Split string in SQL Server 2005+ CLR vs. T-SQL

 

Author:Petter Liu    http://wintersun.cnblogs.com

希望这篇POST对您有帮助。