Question

我必须创建一个sql查询，该查询获取包含字符“|”的名字，中间名或姓的所有用户。所以我做了类似的事情：

SELECT two.id, 
       two.username, 
       one.firstname, 
       one.middlename, 
       one.lastname 
FROM table_one one INNER JOIN table_two two ON two.id = one.id
WHERE one.firstname LIKE '%|%' 
OR one.middlename LIKE '%|%' 
OR one.lastname LIKE '%|%'

此查询在测试环境中运行良好，大约有一千个配置文件，但它在生产环境中超时，其中包含数十万个配置文件，如果不是接近一百万个。

我们正在运行DB2，版本8.2

Answer 1

您可以尝试将搜索拆分为删除OR，因为性能不佳而臭名昭着：

SELECT
  two.id, 
  two.username, 
  one.firstname, 
  one.middlename, 
  one.lastname 
FROM (
  SELECT id, firstname, middlename, lastname
  FROM table_one 
  WHERE one.firstname LIKE '%|%'
  UNION
  SELECT id, firstname, middlename, lastname
  FROM table_one 
  WHERE one.middlename LIKE '%|%'
  UNION
  SELECT id, firstname, middlename, lastname
  FROM table_one 
  WHERE one.lastname LIKE '%|%'
) one
INNER JOIN table_two two ON two.id = one.id

在每个名称列上都有一个索引，每个偶然将在单独的联合查询中使用。

UNION上的使用可以方便地丢弃重复项，因此多个名称列包含管道字符的情况不会导致重复输出。

Answer 2

尝试

SELECT two.id, 
       two.username, 
       one.firstname, 
       one.middlename, 
       one.lastname 
FROM table_one one INNER JOIN table_two two ON two.id = one.id
WHERE POSITION('|',concat(one.firstname,one.middlename,one.lastname),OCTETS)>0

或

SELECT two.id, 
       two.username, 
       one.firstname, 
       one.middlename, 
       one.lastname 
FROM table_one one INNER JOIN table_two two ON two.id = one.id
WHERE POSITION('|',one.firstname,OCTETS)+POSITION('|',one.middlename,OCTETS)+POSITION('|',one.lastname),OCTETS)>0

Sql Query太慢了

2 个答案: