优化慢速SQL查询:基于行类型的派生表和两种不同的连接

Question

我使用Firebird 2.1。我想优化以下查询，因为它执行得非常慢(几乎2秒)，即使是一个小数据集(cca 500条记录):

TABLE Client存储人员和公司/公司组。(ClientType=0 person, ClientType=1 company)主键:ClientID

TABLE ClientContacts存储哪些人链接到哪些公司:ClientID是公司的ID, ContactClientID是链接到公司的人的ID。主键:ClientID, ContactClientID

TABLE CompanyGroups存储哪些公司链接到哪些公司组:ParentClientID是公司组的ID, ClientID是附加到公司组的公司ID。主键:ParentClientID, ClientID

因此，一个人可能属于多个公司，而一个公司可能属于多个公司集团。

我想列出所有的人员和公司。对于person，我想显示它属于哪些公司，对于companys，我想显示该公司属于哪些公司组。

首先，我需要根据个人/公司所属的公司/公司组的名称进行搜索。在Firebird中，由于聚合函数"LIST"，我可以通过派生表实现这一点。

下面是查询:

SELECT C.ClientID,
  C.ClientType,
  C.ClientName,
  IIF(C.ClientType = 0, PCN.PCompanyNames, CCN.CCompanyNames),
FROM Clients C
  LEFT JOIN (SELECT CC.ContactClientID, LIST(CL.ClientName, ', ') AS PCompanyNames
   FROM ClientContacts CC LEFT JOIN Clients CL ON CL.ClientID = CC.ClientID WHERE 
    CL.AccessRights = 0 OR CL.UserID = :UserID OR (CL.AccessRights = 2 AND 
     CL.ClientID IN (SELECT ClientID FROM ClientRights WHERE UserID = :UserID))
      GROUP BY CC.ContactClientID) PCN ON PCN.ContactClientID = C.ClientID AND C.ClientType = 0
  LEFT JOIN (SELECT CG.ClientID, LIST(CL.ClientName, ', ') AS CCompanyNames
   FROM CompanyGroups CG LEFT JOIN Clients CL ON CL.ClientID = CG.ParentClientID WHERE 
    CL.AccessRights = 0 OR CL.UserID = :UserID OR (CL.AccessRights = 2 AND
     CL.ClientID IN (SELECT ClientID FROM ClientRights WHERE UserID = :UserID))
      GROUP BY CG.ClientID) CCN ON CCN.ClientID = C.ClientID AND C.ClientType = 1
WHERE (C.AccessRights = 0
    OR C.UserID = :UserID
      OR (C.AccessRights = 2 AND C.ClientID IN (SELECT ClientID FROM ClientRights WHERE UserID = :UserID)))
  AND (:SearchStr IS NULL
    OR (PCN.PCompanyNames COLLATE UNICODE_CI LIKE '%' || :SearchStr || '%'
    OR CCN.CCompanyNames COLLATE UNICODE_CI LIKE '%' || :SearchStr || '%'))

---

更新查询计划，首先是上面的查询，其次是上面的查询，没有WHERE子句(没有IN SELECT)

Field #01: CLIENTS.CLIENTID Alias:CLIENTID Type:INTEGER
Field #02: CLIENTS.CLIENTTYPE Alias:CLIENTTYPE Type:INTEGER
Field #03: CLIENTS.CLIENTNAME Alias:CLIENTNAME Type:STRING(1000)
Field #04: .CASE Alias:CASE Type:BLOB SUB_TYPE 1
PLAN (PCN CLIENTRIGHTS INDEX (RDB$PRIMARY46))
PLAN (CCN CLIENTRIGHTS INDEX (RDB$PRIMARY46))
PLAN (CLIENTRIGHTS INDEX (RDB$PRIMARY46))
PLAN JOIN (JOIN (C INDEX (IDX_CLIENTS_ACCESSRIGHTS, IDX_CLIENTS_USERID, IDX_CLIENTS_ACCESSRIGHTS), SORT (JOIN (PCN CC NATURAL, PCN CL INDEX (RDB$PRIMARY12)))), SORT (JOIN (CCN CG NATURAL, CCN CL INDEX (RDB$PRIMARY12))))
119643 fetches, 0 marks, 0 reads, 0 writes.
0 inserts, 0 updates, 0 deletes, 19977 index, 19629 seq.
Delta memory: 321686664 bytes.
Total execution time: 1.531s

Field #01: CLIENTS.CLIENTID Alias:CLIENTID Type:INTEGER
Field #02: CLIENTS.CLIENTTYPE Alias:CLIENTTYPE Type:INTEGER
Field #03: CLIENTS.CLIENTNAME Alias:CLIENTNAME Type:STRING(1000)
Field #04: .CASE Alias:CASE Type:BLOB SUB_TYPE 1
PLAN JOIN (JOIN (C NATURAL, SORT (JOIN (PCN CC NATURAL, PCN CL INDEX (RDB$PRIMARY12)))), SORT (JOIN (CCN CG NATURAL, CCN CL INDEX (RDB$PRIMARY12))))
119289 fetches, 0 marks, 0 reads, 0 writes.
0 inserts, 0 updates, 0 deletes, 19646 index, 19832 seq.
Delta memory: 321690896 bytes.
Total execution time: 1.406s

Answer 1

对不起，我不能评论(没有必要的声誉)。没有结构很难做到，但我在努力。

:

1)您需要将查询精确地分为两部分:ClientType = 0和ClientType = 1;

2)在PCN和CCN中不需要左连接，因为它没有意义;

3)你经常使用query:

select ClientID
from Client
where c.AccessRight = 0 or
      c.UserId = :UserId or
      (c.AccessRight = 2 and
       c.ClientId in (
          select r.ClientId
          from ClientRights r
          where r.UserId = :UserId))

我认为你应该这样做:

with
cl as (
   select c.ClientId, c.ClientName, c.ClientType
   from Client c
   where c.AccessRight = 0 or
         c.UserId = :UserId or
         (c.AccessRight = 2 and c.ClientId in (select r.ClientId from ClientRights r where r.UserId = :UserId))),
q2 as (
    select cc.ContactClientId, List (cl.ClientName, ', ') as PCompanyNames
    from ClientContacts cc
         join cl on (cc.ClientId = cl.ClientId)
    group by cc.ContactClientId),
q3 as (
    select cg.ClientId, List (cl.ClientName, ', ') as CCompanyNames
    from CompanyGroups cg
         join cl on (cg.ParentClientId = cl.ClientId)
    group by cg.ClientId)
select cl.ClientId, cl.ClientType, cl.ClientName, q2.PCompanyNames
from cl
     left join q2 on (cl.ClientId = q2.ContactClientId)
where cl.ClientType = 0
  and (q2.PCompanyNames like '%' || Coalesce (:SearchStr, '') || '%' or Coalesce(:SearchStr, '') = '')
union all
select cl.ClientId, cl.ClientType, cl.ClientName, q3.CCompanyNames
from cl
     left join q3 on (cl.ClientId = q3.ClientId)
where cl.ClientType = 1
  and (q3.CCompanyNames like '%' || Coalesce (:SearchStr, '') || '%' or Coalesce(:SearchStr, '') = '')