Question

假设我有一个带有类型列的简单文档表：

Documents
Id  Type
1   A
2   A
3   B
4   C
5   C
6   A
7   A
8   A
9   B
10  C

用户有权访问不同类型的文档：

Permissions
Type    User
A       John
A       Jane
B       Sarah
C       Peter
C       John
C       Mark

我需要在用户之间分发这些文档作为任务：

Tasks
Id  T DocId UserId
1   A   1   John
2   A   2   Jane
3   B   3   Sarah
4   C   4   Peter
5   C   5   John
6   A   6   John
7   A   7   Jane
8   A   8   John
9   B   9   Sarah
10  C   10  Mark

我该怎么做？我如何获得任务？

Answer 1

您可以枚举行，然后使用模运算进行匹配：

with d as (
      select d.*,
             row_number() over (partition by type order by newid()) as seqnum,
             count(*) over (partition by type) as cnt
      from documents d
     ),
      u as (
       select u.*,
              row_number() over (partition by type order by newid()) as seqnum,
              count(*) over (partition by type) as cnt
       from users u
      )
select d.*
from d join
     u
     on d.type = u.type and
        u.seqnum = (d.seqnum % u.cnt) + 1

Answer 2

好问题。

此解决方案返回所有可能的分配，按优先级排序，由所涉及的用户数，每个用户的最低文档数，标准偏差等信息确定每个用户的任务等。
我不指望document.id是一个从1开始的数字序列，因此使用dense_rank。
解决方案的核心是迭代CTE，它生成所有可能分布的记录集。
笔记本电脑上的执行时间约为20秒（迭代部分需要5秒）

with        doc_user    as 
            (
                select          d."id"                                          as docid
                               ,p."user"                                        as userid
                               ,dense_rank  ()  over (order by      d."id")     as doc_seq

                from                documents       d

                        left join   permissions     p

                        on          p.type = d.type
            )

           ,it_cte  as 
            (
                select      docid
                           ,userid
                           ,doc_seq
                           ,cast (coalesce(userid,'') as varchar(max))  as path
                           ,'A'                                         as cte_part

                from        doc_user    

                where       doc_seq = 1


                union all

                select      r.docid
                           ,r.userid
                           ,du.doc_seq
                           ,r.path + ',' + coalesce (du.userid,'')
                           ,'B'


                from                    it_cte      as r

                            cross join  doc_user    as du

                where       du.doc_seq = r.doc_seq + 1


                union all

                select      du.docid
                           ,du.userid
                           ,du.doc_seq
                           ,r.path + ',' + coalesce (du.userid,'')
                           ,'C'


                from                    it_cte      as r

                            cross join  doc_user    as du

                where       du.doc_seq = r.doc_seq + 1
                        and r.cte_part in ('A','C') 
            )

           ,result_sets as
            (
                select      dense_rank  () over (order by path) as set_id   
                           ,docid
                           ,userid

                from        it_cte

                where       doc_seq = (select count(*) from documents)
            )

           ,result_sets_stat as
            (
                select      set_id
                           ,count   (distinct userid)   as users_involved

                from        result_sets

                group by    set_id
            )

           ,result_sets_users_stat as
            (
                select      set_id
                           ,min     (doc)   min_doc_per_user
                           ,stdevp  (doc)   stdevp_doc_per_user

                from       (select      set_id
                                       ,userid
                                       ,count   (*) as doc

                            from        result_sets

                            group by    set_id
                                       ,userid
                            ) t

                group by    set_id
            )

select      s.set_priority
           ,r.docid
           ,r.userid
           ,s.users_involved        
           ,s.min_doc_per_user              
           ,s.stdevp_doc_per_user       

from                    (select     s.set_id
                                   ,s.users_involved        
                                   ,u.min_doc_per_user              
                                   ,u.stdevp_doc_per_user   

                                   ,row_number () over      
                                    (
                                        order by    s.users_involved        desc
                                                   ,u.min_doc_per_user      desc
                                                   ,u.stdevp_doc_per_user   
                                                   ,s.set_id  

                                    )   as set_priority

                        from                    result_sets_stat        as s

                                    join        result_sets_users_stat  as u

                                    on          u.set_id    =
                                                s.set_id
                        ) s

            join        result_sets as r

            on          r.set_id    =
                        s.set_id    

order by    s.set_priority 
           ,r.docid

option      (merge join) 
;

邮编/重复加入？

2 个答案: