SELECT INTO查询使用NOT IN子查询需要较长的时间/挂起

Question

的问题是，这个查询挂起或具有我不知道如何使用的MS Access修复无限记录：

预期的用户输入：

User input Start Date: 1/15/2015 
User input End Date: 11/15/2015 
User input Upper Data Threshold in kB: 50 

源表：

[Master] Table in Access: 
Invc Date Mobile Nbr  PktDtVol 
--------- ----------  -------- 
1/15/15 647-409-8206 48kB 
2/15/15 647-409-8206 33kB 
3/15/15 647-409-8206 8000kB 
4/15/15 647-409-8206 20kB 
5/15/15 647-409-8206 10kB 
6/15/15 647-409-8206 0kB 
7/15/15 718-500-2311 3kB 
8/15/15 718-500-2311 45kB 
9/15/15 718-500-2311 25kB 
10/15/15 514-300-3311 33kB 
11/15/15 514-300-3311 20kB 

输出在[Temp_Table]：

Invc Date Mobile Nbr  PktDtVol Difference in Days 
--------- ----------  -------- ------------------- 
7/15/15 718-500-2311 3kB    304 
8/15/15 718-500-2311 45kB   304 
9/15/15 718-500-2311 25kB   304 
10/15/15 514-300-3311 33kB   304 
11/15/15 514-300-3311 20kB   304 

接受SQL方案产生上述输出：

PARAMETERS [Start Date] DateTime, [End Date] DateTime, [Upper Bound Usage in KB] IEEEDouble; 
SELECT m.[Invc Date], m.PktDtVol, m.[Mobile Nbr], DateDiff("d",[Start Date],[End Date]) AS [Difference in days] 
INTO Temp_Table FROM Master AS m 
WHERE (m.[Invc Date]>=[Start Date] And m.[Invc Date])<=[End Date] AND m.[Mobile Nbr] NOT IN 
(SELECT q.[Mobile Nbr] FROM Master AS q WHERE (q.PktDtVol>=[Upper Bound Usage in KB])); 

从这里，我试图创建一个索引通过另一SQL语句修改表以优化查询，但不工作：

CREATE INDEX Index2 ON Master([Ttl Charges]) 

该查询正常工作，没有挂在源表中的10条记录与多个记录与预期的输出。但是，如果源表中有多条记录的56,000条记录，则会出现此问题。

Answer 1

[Ttl Charges]上的索引不会帮助你，但[PktDtVol]上的索引将会。我只是做了10000行的测试和缺乏[PktDtVol]指数的绝对性能瓶颈：

Indexes: 
    none 
Time: 
    170 seconds (just under 3 minutes) 

Indexes: 
    [Invc Date] 
    [Mobile Number] 
Time: 
    (same as before) 

Indexes: 
    [Invc Date] 
    [Mobile Number] 
    [PktDtVol] 
Time: 
    36 seconds 

支付额外的性能提升，你可以重新制定查询使用LEFT JOIN的，而不是NOT IN子句中带有子查询，如您在评论中提到的：

PARAMETERS [Start Date] DateTime, [End Date] DateTime, [Upper Bound Usage in KB] IEEEDouble; 
SELECT 
    [Master].[Invc Date], 
    [Master].PktDtVol, 
    [Master].[Mobile Nbr], 
    DateDiff("d",[Start Date],[End Date]) AS [Difference in days] 
INTO Temp_Table 
FROM 
    [Master] 
    LEFT OUTER JOIN 
    (
     SELECT DISTINCT q.[Mobile Nbr] FROM Master AS q 
     WHERE (q.PktDtVol>=[Upper Bound Usage in KB]) 
    ) s 
     ON [Master].[Mobile Nbr] = s.[Mobile Nbr] 
WHERE 
    [Master].[Invc Date] >= [Start Date] 
     AND [Master].[Invc Date] <= [End Date] 
     AND s.[Mobile Nbr] IS NULL;