Question

我有一个数据表，如下所示

#data
---------------
Account AccountType
---------------
1       2
2       0
3       5
4       2
5       1
6       5

AccountType 2是标题，5是总计。类型2的含义帐户必须检查下一个1或0以确定其Dim值是1还是0.类型5的总计必须查找最接近的1或0以确定其Dim值。类型1或0的帐户类型为Dim。

类型2的帐户显示为孤岛，因此仅仅检查RowNumber + 1是不够的，同样适用于类型5的帐户。

我使用CTE来到下表。但是找不到快速的方法从这里到我的账户，账户类型，所有账户的Dim的最终结果

T3
-------------------
StartRow  EndRow AccountType  Dim
-------------------
1           1         2        0
2           2         0        0
3           3         5        0
4           4         2        1
5           5         0        1
6           6         5        1

下面的代码是MS TSQL复制粘贴它并查看它运行。 CTE select语句的最终连接速度非常慢，即使是500行也需要30秒。我需要处理100.000行。我做了一个基于游标的解决方案，它可以在10-20秒内完成，可行且快速递归CTE解决方案，在5秒内完成100.000行，但它依赖于#data表的碎片。我应该补充说，这是简化的，真正的问题有很多需要考虑的维度。但是对于这个简单的问题它也会起作用。

无论如何，使用连接或其他基于集合的解决方案有一种快速的方法。

SET NOCOUNT ON

IF OBJECT_ID('tempdb..#data') IS NOT NULL
    DROP TABLE #data

CREATE TABLE #data
(
Account INTEGER IDENTITY(1,1),
AccountType INTEGER,
)

BEGIN -- TEST DATA
DECLARE @Counter INTEGER = 0
DECLARE @MaxDataRows INTEGER = 50 -- Change here to check performance
DECLARE @Type INTEGER
    WHILE(@Counter < @MaxDataRows)
    BEGIN
    SET @Type = CASE 
        WHEN @Counter % 10 < 3 THEN 2 
        WHEN @Counter % 10 >= 8 THEN 5 
        WHEN @Counter % 10 >= 3 THEN (CASE WHEN @Counter < @MaxDataRows / 2.0 THEN 0 ELSE 1 END )
        ELSE 0 
        END
    INSERT INTO #data VALUES(@Type)
    SET @Counter = @Counter + 1
    END
END -- TEST DATA END



;WITH groupIds_cte AS
(
    SELECT *,
    ROW_NUMBER() OVER (PARTITION BY AccountType ORDER BY Account) - Account AS GroupId  
    FROM #data
),

islandRanges_cte AS
(
SELECT
    MIN(Account) AS StartRow,
    MAX(Account) AS EndRow,
    AccountType
FROM groupIds_cte
GROUP BY GroupId,AccountType
),

T3 AS
(
SELECT I.*, J.AccountType AS Dim
FROM islandRanges_cte I
INNER JOIN islandRanges_cte J
ON (I.EndRow + 1 = J.StartRow AND I.AccountType = 2)
UNION ALL
SELECT I.*, J.AccountType AS Dim
FROM islandRanges_cte I
INNER JOIN islandRanges_cte J
ON (I.StartRow - 1 = J.EndRow AND I.AccountType = 5)
UNION ALL
SELECT *, AccountType AS Dim
FROM islandRanges_cte
WHERE AccountType = 0 OR AccountType = 1
),

T4 AS 
(
SELECT Account, Dim
    FROM (
    SELECT FlattenRow AS Account, StartRow, EndRow, Dim
    FROM T3 I   
    CROSS APPLY (VALUES(StartRow),(EndRow)) newValues (FlattenRow)
    ) T
)

--SELECT * FROM T3 ORDER BY StartRow
--SELECT * FROM T4 ORDER BY Account

-- Final correct result but very very slow
SELECT D.Account, D.AccountType, I.Dim FROM T3 I
INNER JOIN #data D
ON D.Account BETWEEN I.StartRow AND I.EndRow
ORDER BY Account

通过一些时间测试进行编辑

SET NOCOUNT ON

IF OBJECT_ID('tempdb..#data') IS NULL
CREATE TABLE #times
(
RecId INTEGER IDENTITY(1,1),
Batch INTEGER,
Method NVARCHAR(255),
MethodDescription NVARCHAR(255),
RunTime INTEGER
)

IF OBJECT_ID('tempdb..#batch') IS NULL
CREATE TABLE #batch 
(
Batch INTEGER IDENTITY(1,1),
Bit BIT
)

INSERT INTO #batch VALUES(0)

IF OBJECT_ID('tempdb..#data') IS NOT NULL
    DROP TABLE #data

CREATE TABLE #data
(
Account INTEGER
)

CREATE NONCLUSTERED INDEX data_account_index ON #data (Account)

IF OBJECT_ID('tempdb..#islands') IS NOT NULL
    DROP TABLE #islands

CREATE TABLE #islands
(
AccountFrom INTEGER ,
AccountTo INTEGER,
Dim INTEGER,
)

CREATE NONCLUSTERED INDEX islands_from_index ON #islands (AccountFrom, AccountTo, Dim)

BEGIN -- TEST DATA
    INSERT INTO #data
    SELECT TOP 100000 ROW_NUMBER() OVER(ORDER BY t1.number) AS N
    FROM master..spt_values t1 
    CROSS JOIN master..spt_values t2

    INSERT INTO #islands
    SELECT MIN(Account) AS Start, MAX(Account), Grp
    FROM (SELECT *, NTILE(10) OVER (ORDER BY Account) AS Grp FROM #data) T
    GROUP BY Grp ORDER BY Start
END -- TEST DATA END

--SELECT * FROM #data
--SELECT * FROM #islands

--PRINT CONVERT(varchar(20),DATEDIFF(MS,@RunDate,GETDATE()))+' ms Sub Query'
DECLARE @RunDate datetime
SET @RunDate=GETDATE()

SELECT Account, (SELECT Dim From #islands WHERE Account BETWEEN AccountFrom AND AccountTo) AS Dim
FROM #data

INSERT INTO #times VALUES ((SELECT MAX(Batch) FROM #batch) ,'subquery','',DATEDIFF(MS,@RunDate,GETDATE()))
SET @RunDate=GETDATE()

SELECT D.Account, V.Dim
FROM #data D
CROSS APPLY
(
SELECT Dim From #islands V
WHERE D.Account BETWEEN V.AccountFrom AND V.AccountTo
) V

INSERT INTO #times VALUES ((SELECT MAX(Batch) FROM #batch) ,'crossapply','',DATEDIFF(MS,@RunDate,GETDATE()))
SET @RunDate=GETDATE()

SELECT D.Account, I.Dim 
FROM #data D
JOIN #islands I
ON D.Account BETWEEN I.AccountFrom AND I.AccountTo

INSERT INTO #times VALUES ((SELECT MAX(Batch) FROM #batch) ,'join','',DATEDIFF(MS,@RunDate,GETDATE()))
SET @RunDate=GETDATE()

;WITH cte AS
(
SELECT Account, AccountFrom, AccountTo, Dim, 1 AS Counting
FROM #islands
CROSS APPLY (VALUES(AccountFrom),(AccountTo)) V (Account)
UNION ALL
SELECT Account + 1 ,AccountFrom, AccountTo, Dim, Counting + 1
FROM cte
WHERE (Account + 1) > AccountFrom AND (Account + 1) < AccountTo
)
SELECT Account, Dim, Counting FROM cte OPTION(MAXRECURSION 32767)

INSERT INTO #times VALUES ((SELECT MAX(Batch) FROM #batch) ,'recursivecte','',DATEDIFF(MS,@RunDate,GETDATE()))

您可以从#times表中选择以查看运行时间：）

Answer 1

我认为你想要一个联盟，但是使用不平等而不是平等：

select tt.id, tt.dim1, it.dim2
from TallyTable tt join
     IslandsTable it
     on tt.id between it."from" and it."to"

这适用于您在问题中提供的数据。

这是另一个可能有用的想法。这是查询：

select d.*,
       (select top 1 AccountType from #data d2 where d2.Account > d.Account and d2.AccountType not in (2, 5)
       ) nextAccountType
from #data d 
order by d.account;

我刚刚在50,000行上运行了这个版本，这个版本在我的系统上耗时17秒。将表格更改为：

CREATE TABLE #data (
    Account INTEGER IDENTITY(1,1) primary key,
    AccountType INTEGER,
);

实际上已经减慢到大约1:33 - 令我惊讶的是。也许其中一个会帮助你。

SQL Server 2008填补了维度的空白

1 个答案: