1

我们有一个事务 sql 语句，它查询 4 ​​个表，每个表有数百万行。

尽管根据 TuningAdvisor 已使用索引和统计数据对其进行了优化，但仍需要几分钟时间。

查询的结构如下：

SELECT E.EmployeeName
    , SUM(M.Amount) AS TotalAmount
    , SUM(B.Amount) AS BudgetAmount
    , SUM(T.Hours) AS TotalHours
    , SUM(TB.Hours) AS BudgetHours
    , SUM(CASE WHEN T.Type = 'Waste' THEN T.Hours ELSE 0 END) AS WastedHours
来自员工 E
左加入 MoneyTransactions M
    ON E.EmployeeID = M.EmployeeID
LEFT JOIN BudgetTransactions B
    ON E.EmployeeID = B.EmployeeID
LEFT JOIN TimeTransactions T
    ON E.EmployeeID = T.EmployeeID
左加入 TimeBudgetTransactions TB
    ON E.EmployeeID = TB.EmployeeID
GROUP BY E.EmployeeName

由于每个事务表包含数百万行，我考虑将其拆分为每个事务表一个查询，使用表变量，如@real,@budget和@hours，然后将它们连接到一个 final 中SELECT。但在测试中它似乎没有加速。

您将如何处理以加快速度？

4

3 回答 3

8

我不确定您发布的查询是否会产生您期望的结果。

它将交叉连接所有维度表（MoneyTransactions 等）并将所有结果相乘。

试试这个：

SELECT  E.EmployeeName,
        (
        SELECT  SUM(amount)
        FROM    MoneyTransactions m
        WHERE   M.EmployeeID = E.EmployeeID
        ) AS TotalAmount,
        (
        SELECT  SUM(amount)
        FROM    BudgetTransactions m
        WHERE   M.EmployeeID = E.EmployeeID
        ) AS BudgetAmount,
        (
        SELECT  SUM(hours)
        FROM    TimeTransactions m
        WHERE   M.EmployeeID = E.EmployeeID
        ) AS TotalHours,
        (
        SELECT  SUM(hours)
        FROM    TimeBudgetTransactions m
        WHERE   M.EmployeeID = E.EmployeeID
        ) AS BudgetHours
FROM    Employees E
于 2009-04-07T10:04:50.243 回答
1

我不知道您的表上是否有所有可以加快处理速度的索引，但是拥有大表可能会对查询时间产生这种影响。如果可能，我建议对表进行分区。这是更多的工作，但是您为加快查询所做的一切现在在几百万条新记录之后还不够。

于 2009-04-07T10:17:27.687 回答
0

试试这个：

SELECT E.EmployeeName, TA.TotalAmount, BA.BudgetAmount, TWH.TotalHours, BH.BudgetHours, TWH.WastedHours
FROM Employees E
LEFT JOIN 
(SELECT E.EmployeeID, SUM(M.Amount) AS TotalAmount
FROM Employees E INNER JOIN MoneyTransactions M ON E.EmployeeID = M.EmployeeID GROUP BY E.EmployeeID)TA
ON E.EmployeeID = TA.EmployeeID
LEFT JOIN 
(SELECT E.EmployeeID , SUM(B.Amount) AS BudgetAmount
FROM Employees E INNER JOIN BudgetTransactions B ON E.EmployeeID = B.EmployeeID GROUP BY E.EmployeeID)BA
ON E.EmployeeID = BA.EmployeeID
LEFT JOIN 
(SELECT E.EmployeeID , SUM(T.Hours) AS TotalHours , SUM(CASE WHEN T.Type = 'Waste' THEN T.Hours ELSE 0 END) AS WastedHours
FROM Employees E INNER JOIN TimeTransactions T ON E.EmployeeID = T.EmployeeID GROUP BY E.EmployeeID)TWH
ON E.EmployeeID = TWH.EmployeeID
LEFT JOIN 
(SELECT E.EmployeeID , SUM(TB.Hours) AS BudgetHours
FROM Employees E INNER JOIN TimeBudgetTransactions TB ON E.EmployeeID = TB.EmployeeID GROUP BY E.EmployeeID)BH
ON E.EmployeeID = BH.EmployeeID
于 2018-07-20T13:45:12.917 回答