0

使用 SQL Server 2016 及更高版本

我目前正在评估两种显示搜索结果的方法。显示所有符合“标准”的“产品”。

我正在研究将符合条件的 ID 列表存储在临时表中的优点，然后加入我的主要产品与动态创建的会话视图，其中 ID 编码为值。

下面的脚本示例。我省略了主要产品表本身，因为它只是一个大的平面表，但确实包含公司专有的详细信息。代码本身不是问题，而是它生成的统计信息。

SET STATISTICS IO, TIME OFF;

DROP TABLE IF EXISTS dba.Temp;
DROP VIEW IF EXISTS dba.Test1;
DROP VIEW IF EXISTS dba.Test2;

CREATE TABLE dba.Temp (ProductID INT);

INSERT INTO dba.Temp (ProductID)
SELECT  TOP 1000
        ProductID
  FROM  dbo.Products
 ORDER BY NEWID();
GO

CREATE VIEW dba.Test1
AS
    SELECT  P.*
      FROM  Products P
      JOIN  dba.Temp T ON T.ProductID = P.ProductID;
GO

DECLARE @strSQL AS NVARCHAR(MAX);

SET @strSQL = N'';

SELECT  @strSQL = @strSQL + N',(' + CAST(ProductID AS NVARCHAR(MAX)) + N')'
  FROM  dba.Temp;

SET @strSQL = STUFF(@strSQL, 1, 1, ('CREATE VIEW dba.Test2 AS SELECT P.* FROM Products P JOIN (VALUES ')) + N') T (ProductID) ON T.ProductID = P.ProductID';

EXEC sp_executesql @stmt = @strSQL;
GO

SET STATISTICS IO, TIME ON;

PRINT '------------------------------ Test 1'; 
SELECT * FROM dba.Test1; 
PRINT '------------------------------ Test 2'; 
SELECT * FROM dba.Test2; 
PRINT '------------------------------ End';

SET STATISTICS IO, TIME OFF;

我发现我的数据集上的两个选项之间几乎没有区别，但是根据我的测试方式，我得到了一些非常奇怪的结果。

如果我只从测试 1 中读取数据，我会收到与以下类似的统计数据，但经过时间的波动很小 - 我不是服务器上唯一的用户。

SQL Server parse and compile time: 
   CPU time = 8 ms, elapsed time = 8 ms.
------------------------------ Test 1

 SQL Server Execution Times:
   CPU time = 0 ms,  elapsed time = 0 ms.

(1000 rows affected)
Table 'Products'. Scan count 0, logical reads 3071, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'Temp'. Scan count 1, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.

 SQL Server Execution Times:
   CPU time = 47 ms,  elapsed time = 56 ms.

运行测试 2，我收到了非常相似的结果，只有较低的 IO（预期为临时表没有被读取）

SQL Server parse and compile time: 
   CPU time = 46 ms, elapsed time = 46 ms.
------------------------------ Test 2

 SQL Server Execution Times:
   CPU time = 0 ms,  elapsed time = 0 ms.

(1000 rows affected)
Table 'Products'. Scan count 0, logical reads 3071, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.

 SQL Server Execution Times:
   CPU time = 47 ms,  elapsed time = 57 ms.

然而，同时运行这两个测试，我看到第二个运行查询的结果始终较慢。

SQL Server parse and compile time: 
   CPU time = 0 ms, elapsed time = 0 ms.
------------------------------ Test 1

 SQL Server Execution Times:
   CPU time = 0 ms,  elapsed time = 0 ms.

(1000 rows affected)
Table 'Products'. Scan count 0, logical reads 3063, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'Temp'. Scan count 1, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.

 SQL Server Execution Times:
   CPU time = 47 ms,  elapsed time = 56 ms.
------------------------------ Test 2

 SQL Server Execution Times:
   CPU time = 0 ms,  elapsed time = 0 ms.

(1000 rows affected)
Table 'Products'. Scan count 0, logical reads 3063, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.

 SQL Server Execution Times:
   CPU time = 62 ms,  elapsed time = 200 ms.
------------------------------ End

 SQL Server Execution Times:
   CPU time = 0 ms,  elapsed time = 0 ms.

第二个查询的结果偏斜是否有任何合乎逻辑的原因？是否第一个查询正在创建影响第二个查询的负载？我想知道我是否遗漏了什么或有根本的误解。这就是我通常会如何调整我的流程，强调 IO，关注时间。如果我需要调整我的调音方法，那么我们将不胜感激地收到任何建议。

4

0 回答 0