mysql - 我将如何优化这个 WordPress 查询？

Question

我正在尝试找出下面查询的最佳索引组合。现在是使用临时的；使用文件排序并杀死我的 vps。查询需要 6-10 秒。

SELECT SQL_CALC_FOUND_ROWS 
  wp_posts.ID     
FROM 
  wp_posts
  INNER JOIN wp_term_relationships ON (wp_posts.ID = wp_term_relationships.object_id)
  INNER JOIN wp_term_taxonomy ON (wp_term_relationships.term_taxonomy_id = wp_term_taxonomy.term_taxonomy_id)
  INNER JOIN wp_terms ON (wp_term_taxonomy.term_id = wp_terms.term_id) 
WHERE
  1=1
  AND wp_term_taxonomy.taxonomy = 'post_tag' 
  AND wp_terms.slug IN ('pie') 
  AND wp_posts.post_type = 'post'
  AND (wp_posts.post_status = 'publish') 
GROUP BY 
  wp_posts.ID     
ORDER BY 
  wp_posts.post_date DESC 
LIMIT 0, 20

有什么建议吗？

Answer 1

这在性能方面比较如何？

SELECT
  p.ID
FROM 
  wp_posts AS p
WHERE
  1=1
  AND p.post_type = 'post'
  AND p.post_status = 'publish'
  AND EXISTS (
    SELECT 1 
      FROM wp_term_relationships AS r 
           INNER JOIN wp_term_taxonomy AS t ON 
             r.term_taxonomy_id = t.term_taxonomy_id AND t.taxonomy = 'post_tag'
           INNER JOIN wp_terms AS m ON 
             m.term_id = t.term_id AND m.slug IN ('pie') 
     WHERE r.object_id = wp_posts.ID 
  )
ORDER BY 
  p.post_date DESC 
LIMIT 0, 20

索引应位于所有主键和外键、wp_terms.slug、wp_term_taxonomy.taxonomy 以及 wp_posts.post_status、post_type 上的复合索引，post_date。