Netezza排除特定记录

Question

我在以下格式的netezza的web_event表中有一些数据。

vstr_id | sessn_id | sessn_ts   | wbpg_nm 
V1  | V1S1  | 02-02-2015 09:20:00 | /home/login 
V1  | V1S1  | 02-02-2015 09:22:00 | -1 
V1  | V1S1  | 02-02-2015 09:30:00 | /home/contacts 
V1  | V1S1  | 02-02-2015 09:32:00 | -1 
V1  | V1S1  | 02-02-2015 09:50:00 | /home/search 
V1  | V1S1  | 02-02-2015 09:55:00 | -1 
V2  | V2S1  | 02-02-2015 09:10:00 | /home 
V2  | V2S1  | 02-02-2015 09:15:00 | /home/apps 
V2  | V2S2  | 02-02-2015 09:20:00 | /home/news 
V2  | V2S2  | 02-02-2015 09:23:00 | /home/news/internal 

这是我的源表。

我想使用该web_event表并创建像下面这样的另一个表。

我想要像下面那样加载sessn_durtn表和time_on_pg表。

1）time_on_page列：它是当前页面和下一页面加载之间的时间差，如果没有其他事件或页面加载，则会话的最后一页可以有0秒。它可以用几分钟或几秒来表示。

Insert into time_on_pg (select VSTR_ID, 
      SESSN_ID, 
      sessn_ts, 
      WBPG_NM, 
      ????? as time_on_page 
      from web_event) 

vstr_id | sessn_id | sessn_ts   | wbpg_nm    | wanted_time_on_page | currently_known_time_on_page 
V1  | V1S1  | 02-02-2015 09:20:00 | /home/login   | 10mins    | 2mins 
V1  | V1S1  | 02-02-2015 09:22:00 | -1     |      | 8mins 
V1  | V1S1  | 02-02-2015 09:30:00 | /home/contacts  | 20mins    | 2mins 
V1  | V1S1  | 02-02-2015 09:32:00 | -1     |      | 18mins 
V1  | V1S1  | 02-02-2015 09:50:00 | /home/search   | 5mins    | 5mins 
V1  | V1S1  | 02-02-2015 09:55:00 | -1     |      | 

V2  | V2S1  | 02-02-2015 09:10:00 | /home    | 5mins    | 5mins 
V2  | V2S1  | 02-02-2015 09:15:00 | /home/apps   |      | 

V2  | V2S2  | 02-02-2015 09:20:00 | /home/news   | 3mins    | 3mins 
V2  | V2S2  | 02-02-2015 09:23:00 | /home/news/internal |      | 

我们怎样才能在Netezza公司或任何SQL查询做到这一点？

我必须计算使用

SELECT vstr_id, 
    sessn_id, 
    sessn_ts, 
    wbpg_nm, 
    ???????? AS wanted_time_on_page, 
    extract(epoch from (lag(event_ts) over (partition by vstr_id, sessn_id order by event_ts DESC) - event_ts)) AS currently_known_time_on_page 
    from web_event; 

wanted_time_on_page和currently_known_time_on_page之间的主要差别的currently_known_time_on_page的逻辑被消除“-1”的网页而计算除了最后一页的时间差。

Answer 1

我不知道如何大数据集，以及如何你有很多可用的RAM。这个查询是在内存中完成的。您可以将每个单独的CTE转换为临时表以获得速度。

WITH CTE_SessionOrder AS (
SELECT 
    sessn_id 
    ,sessn_ts  
    ,wbpg_nm 
    ,ROW_NUMBER() OVER(PARTITION BY sessn_id ORDER BY sessn_ts DESC) AS RowNum -- This is sorted Desc to get last row 
FROM 
    web_event 
) 
,CTE_KeepLastRow AS (
SELECT * 
FROM 
    CTE_SessionOrder 
WHERE 
    RowNum = 1 
    AND wbpg_nm = '-1' 
) 
,CTE_OtherRows AS (
SELECT * 
FROM 
    CTE_SessionOrder 
WHERE 
    wbpg_nm != '-1' 
) 
,CTE_FilteredData AS (
SELECT sessn_id,sessn_ts,wbpg_nm FROM CTE_KeepLastRow 
UNION 
SELECT sessn_id,sessn_ts,wbpg_nm FROM CTE_OtherRows 
) 
,CTE_FilterOrderedData AS (
SELECT 
    * 
    ,ROW_NUMBER() OVER(PARTITION BY sessn_id ORDER BY sessn_ts) AS RowNum -- Now Ordered Asc 
FROM 
    CTE_FilteredData 
) 
,CTE_FinalData AS (
SELECT 
    D1.sessn_id 
    ,D1.sessn_ts  
    ,D1.wbpg_nm 
    ,DATEDIFF(mi,D1.sessn_ts,D2.sessn_ts) time_on_page 
FROM 
    CTE_FilterOrderedData D1 
    LEFT JOIN CTE_FilterOrderedData D2 
     ON D1.sessn_id = D2.sessn_id 
      AND D1.RowNum + 1 = D2.RowNum 
UNION 
SELECT 
    sessn_id 
    ,sessn_ts  
    ,wbpg_nm 
    ,CAST(NULL AS INT) time_on_page 
FROM 
    CTE_SessionOrder 
WHERE 
    RowNum != 1 
    AND wbpg_nm = '-1' 
) 
SELECT * 
FROM 
    CTE_FinalData 

Answer 2

我认为event_ts和sessn_ts是一样的？无论如何，这里是一个查询，应该为你工作，它使用OUTER APPLY技术来查找(> sessn_ts)不是网页-1后表中的结果，然后得到最高结果的升序。

只需将表名改为您的表。

这是一个主要使用outer apply的解决方案，但也使用公用表表达式（cte）来设置所需的最后'-1'的时间。

;WITH cteMaxNeg1 AS (
    SELECT 
     sessn_id 
     ,MaxNeg1SessnTs = MAX(CASE WHEN we.webpg_nm = '-1' THEN we.sessn_ts ELSE NULL END) 
     ,MaxPageSessnTs = MAX(CASE WHEN we.webpg_nm <> '-1' THEN we.sessn_ts ELSE NULL END) 
    FROM 
     @WebEvents we 
    GROUP BY 
     sessn_id 
) 

SELECT 
    we.* 
    ,currently_known_time_on_page = ISNULL(LAG(we.sessn_ts) over (partition by we.vstr_id, we.sessn_id order by we.sessn_ts DESC) - we.sessn_ts,CAST(0 AS DATETIME)) 
    ,WantedTimeOnPage = CASE 
     WHEN we.sessn_ts = m.MaxPageSessnTs AND we.webpg_nm <> '-1' THEN DATEDIFF(MINUTE,we.sessn_ts,m.MaxNeg1SessnTs) 
     WHEN we.webpg_nm <> '-1' THEN DATEDIFF(MINUTE,we.sessn_ts,o.sessn_ts) 
     ELSE NULL 
    END 
FROM 
    @WebEvents we 
    LEFT JOIN cteMaxNeg1 m 
    ON we.sessn_id = m.sessn_id 
    OUTER APPLY (
     SELECT TOP 1sessn_ts 
     FROM 
      @WebEvents i 
     WHERE 
      i.webpg_nm <> '-1' 
      AND i.sessn_id = we.sessn_id 
      AND i.sessn_ts > we.sessn_ts 

     ORDER BY 
      i.sessn_ts ASC 

    ) o 
ORDER BY 
    we.sessn_id 
    ,we.sessn_ts 

这里只是使用CTE和窗口功能

;WITH cte AS (
    SELECT 
     * 
     ,RowNum = ROW_NUMBER() OVER (PARTITION BY sessn_id, IIF(webpg_nm = '-1',0,1) ORDER BY sessn_ts) 
     ,LastNeg1RowNum = ROW_NUMBER() OVER (PARTITION BY sessn_id, IIF(webpg_nm = '-1',0,1) ORDER BY sessn_ts DESC) 
    FROM 
     @WebEvents 
) 

SELECT 
    c1.* 
    ,WantedTimeOnPage = CASE 
     WHEN c1.LastNeg1RowNum = 1 AND c1.webpg_nm <> '-1' THEN DATEDIFF(MINUTE,c1.sessn_ts,c3.sessn_ts) 
     WHEN c1.webpg_nm <> '-1' THEN DATEDIFF(MINUTE,c1.sessn_ts,c2.sessn_ts) 
     ELSE NULL 
    END 
FROM 
    cte c1 
    LEFT JOIN cte c2 
    ON c1.sessn_id = c2.sessn_id 
    AND (c1.RowNum + 1) = c2.RowNum 
    AND c2.webpg_nm <> '-1' 
    LEFT JOIN cte c3 
    ON c1.sessn_id = c3.sessn_id 
    AND c3.LastNeg1RowNum = 1 
    AND c3.webpg_nm = '-1' 
ORDER BY 
    c1.sessn_id 
    ,c1.sessn_ts 

测试数据我从你使用的解决方案：

DECLARE @WebEvents AS TABLE (vstr_id CHAR(2), sessn_id CHAR(5), sessn_ts DATETIME, webpg_nm VARCHAR(100)) 

INSERT INTO @WebEvents (vstr_id, sessn_id, sessn_ts, webpg_nm) 
VALUES 
('V1','V1S1','02-02-2015 09:20:00','/home/login') 
,('V1','V1S1','02-02-2015 09:22:00','-1') 
,('V1','V1S1','02-02-2015 09:30:00','/home/contacts') 
,('V1','V1S1','02-02-2015 09:32:00','-1') 
,('V1','V1S1','02-02-2015 09:50:00','/home/search') 
,('V1','V1S1','02-02-2015 09:55:00','-1') 
,('V2','V2S1','02-02-2015 09:10:00','/home') 
,('V2','V2S1','02-02-2015 09:15:00','/home/apps') 
,('V2','V2S2','02-02-2015 09:20:00','/home/news') 
,('V2','V2S2','02-02-2015 09:23:00','/home/news/internal')