带有部分匹配项或子选择项的Clickhouse LEFT JOIN

如何解决带有部分匹配项或子选择项的Clickhouse LEFT JOIN

实际上，CH不支持带有部分匹配（字符串之类）的左连接，所以我试图在表达式列表中使用select子句构建查询，但它不起作用。 也许（对我而言）有一种全新的方式来执行此操作，但是我只是在了解如何执行此操作的线索。

错误是“在处理查询时缺少列：'DomainName'”

select NumberInTypes,DomainName,Url,(select aa.group_name
        from (select t1.id,t1.url_part,ugu.name as group_name
              from Url t1
                       any
                       left join (select id,urlgroup_id,url_id,ug.name
                                  from UrlGroupUrl t2
                                           any
                                           left join (select id,name
                                                      from UrlGroup t3
                                      ) ug on t2.urlgroup_id = ug.id
                  ) ugu on t1.id = ugu.url_id) aa where t1.Url like '%' || aa.url_part || '%'
        ) as UrlGroup,KeywordId,ResultId,HashedContent,SearchEngine,client_name,project_name,group_name,DateParsed
from PositionNew t1
         any
         left join (
    select id as KeywordId,trimBoth(keyword) as keyword,groupid,client_name
    from Keyword
             any
             left join (
        select keywordgroup_id as groupid,keyword_id as KeywordId,client_name
        from KeywordGroupKeyword
                 any
                 left join (
            select id as groupid,name as group_name,project_id,client_name
            from KeywordGroup
                     any
                     left join (
                select id as project_id,name as project_name,client_id,client_name
                from Project
                         any
                         left join (
                    select id as client_id,name as client_name from Client
                    ) client using client_id
                ) project using project_id
            ) kgroup using groupid
        ) keywordgroup using KeywordId
    ) keyword using KeywordId
where DateParsed between '2020-07-13' and '2020-08-02'
  and PositionType in (1,3)
  and client_name like '%ClientName%'
ORDER BY ResultId,NumberInType
LIMIT
    1 BY ResultId,DomainName;

更新： 显然，您无法在Clickhouse的相关子查询中使用out查询中的列。因此，我完全没有选择余地，开始认为这是不可能的。

重现该问题的简化示例：

第一个表包含Urls

+------------------------------------+
| Url                                |
+------------------------------------+
| https://example.com/cat/page1.html |
+------------------------------------+
| https://example.com/cat/page2.html |
+------------------------------------+
| https://example2.com/page.html     |
+------------------------------------+

第二个表包含UrlGroups

+-----------------+-----------+
| UrlPart         | GroupName |
+-----------------+-----------+
| example.com/cat | DomainCat |
+-----------------+-----------+
| example2.com    | Domain2   |
+-----------------+-----------+

我想要实现的是：

+------------------------------------+-----------+
| Url                                | GroupName |
+------------------------------------+-----------+
| https://example.com/cat/page1.html | DomainCat |
+------------------------------------+-----------+
| https://example.com/cat/page2.html | DomainCat |
+------------------------------------+-----------+
| https://example2.com/page.html     | Domain2   |
+------------------------------------+-----------+

所有左联接-不起作用，因为它需要完全匹配 SUBQUERY-无法使用，因为您无法使用外部查询中的列来过滤其结果

解决方法

让我们依靠数组操作：

WITH 
    (
        SELECT (groupArray(UrlPart),groupArray(GroupName))
        FROM 
        (
            /* Emulate 'UrlGroups' table. */
            SELECT 
                data.1 AS UrlPart,data.2 AS GroupName
            FROM 
            (
                SELECT arrayJoin([
                  ('example.com/cat','DomainCat'),('example2.com','Domain2')]) AS data
            )
        )
    ) AS urls_groups
SELECT 
    Url,arrayElement(
      urls_groups.2,multiSearchFirstIndexCaseInsensitiveUTF8(Url,urls_groups.1)) AS GroupName
FROM 
(
    /* Emulate 'Urls' table. */
    SELECT data AS Url
    FROM 
    (        
        SELECT arrayJoin([
          'https://example.com/cat/page1.html','https://example.com/cat/page2.html','https://example2.com/page.html','https://example_unknown.com/page.html']) AS data          
    )
)

/*
┌─Url───────────────────────────────────┬─GroupName─┐
│ https://example.com/cat/page1.html    │ DomainCat │
│ https://example.com/cat/page2.html    │ DomainCat │
│ https://example2.com/page.html        │ Domain2   │
│ https://example_unknown.com/page.html │           │
└───────────────────────────────────────┴───────────┘
*/

您应该定义要使用的功能-multiSearchFirstIndexCaseInsensitiveUTF8或multiSearchFirstIndexCaseInsensitive。