mysql - 优化用于搜索文章的 sql 查询

Question

我有一个用于搜索数据库的查询。查询在代码中构建并且术语被参数化，因此一切都运行良好且安全。我这么说是因为术语不能来自表格，因为它们是根据用户在搜索字段中输入的内容生成的。

一切正常，我只是想知道是否有更好/更快的方法来执行搜索。

SELECT
  sum(score * multiplier) score,
  a.id,
  a.title
FROM
(
  SELECT 3 score, 'a railway employee' term UNION ALL
  SELECT 2 score, 'railway employee' term UNION ALL
  SELECT 2 score, 'a railway' term UNION ALL
  SELECT 1 score, 'employee' term UNION ALL
  SELECT 1 score, 'railway' term UNION ALL
  SELECT 0 score, 'a' term
) terms
CROSS JOIN
(
  SELECT 'title' TYPE, 1 multiplier
  UNION ALL SELECT 'summary', 1.1
  UNION ALL SELECT 'detail', 1.5
) X
INNER JOIN
(
  SELECT id, 'title' TYPE, title SEARCH FROM article
  UNION ALL
  SELECT id, 'summary' TYPE, summary SEARCH FROM article WHERE summary <> ''
  UNION ALL
  SELECT artId, 'detail' TYPE, txt SEARCH FROM articleSections
) s ON s.TYPE = x.TYPE AND SEARCH LIKE concat('%', terms.term, '%')
INNER JOIN article a ON a.id = s.id
GROUP BY id, title
ORDER BY score DESC;
;

功能简单的演示在 sqlfiddle 上.

Answer 1

您的查询对我来说看起来不错。但是，如果您愿意通过为 UNION 的每个部分重复连接条件来以可读性换取性能，您可以获得更好的执行计划:

....
INNER JOIN
(
  SELECT id, 'title' TYPE, title SEARCH FROM article
   where title like '%a railway employee%' or 
  title like '%railway employee%' 
  or title like '%a railway%'
  or title like '%employee%'
  or title like '%railway%'
  or title like '%a%'
  UNION ALL ....