如何优化此查询并使其执行得更快？ [关闭]答案

【问题标题】：How can I optimize this query and make it execute faster? [closed]如何优化此查询并使其执行得更快？ [关闭]
【发布时间】：2013-01-05 07:11:19
【问题描述】：

如何通过此查询获得更快的结果？

SELECT
    post_id
FROM
    wp_postmeta
WHERE
    meta_key='wpcf-cooler-name' AND (
        post_id IN (
            SELECT 
                post_id
            FROM
                wp_postmeta
            WHERE
                meta_key='wpcf-cooler-name' AND
                meta_value LIKE '%sosa%' AND (
                    post_id IN (
                        SELECT
                            object_id AS 'post_id'
                        FROM
                            wp_term_relationships
                        WHERE 
                            term_taxonomy_id=227
                    )
                ) AND (
                    post_id IN (
                        SELECT
                            ID AS 'post_id'
                        FROM
                            wp_posts
                        WHERE 
                            post_type='cooler' AND
                            post_status='publish'
                    )
                )
        )
    ) ORDER BY meta_value ASC

我的数据库有超过 15000 个条目。因此，显示结果需要时间。

【问题讨论】：

你不能使用 JOIN 代替子查询吗？另外，确保所有相关字段都已编入索引，例如 meta_key、post_id、term_taxonomy_id...
您需要向我们展示表和索引定义。 诊断慢查询需要完整的表和索引定义，而不仅仅是描述或解释。也许您的表格定义不佳。也许索引没有正确创建。也许您认为您在该列上没有索引。没有看到表和索引定义，我们无法分辨。
这看起来很像一堆 WordPress 表和列名？

标签： mysql sql select query-optimization

【解决方案1】：

使用WHERE 条件：

SELECT
  post.id
FROM
  wp_posts as post, wp_postmeta as postmeta, wp_term_relationships as relationships
WHERE
  postmeta.meta_key='wpcf-cooler-name'
  AND postmeta.meta_value LIKE '%sosa%'
  AND relationships.object_id = post.post_id
  AND relationships.term_taxonomy_id = 227
  AND post.ID = postmeta.post_id
  AND post.post_type = 'cooler'
  AND post.post_status='publish'
ORDER BY postmeta.meta_value ASC

【讨论】：

【解决方案2】：

试试这个：

SELECT wp.post_id 
FROM wp_postmeta wp 
INNER JOIN (SELECT object_id AS 'post_id' 
            FROM wp_term_relationships 
            WHERE term_taxonomy_id = 227 
        UNION  
            SELECT ID AS 'post_id' 
            FROM wp_posts 
            WHERE post_type = 'cooler' AND post_status = 'publish') A ON wp.post_id = A.post_id
WHERE wp.meta_key = 'wpcf-cooler-name' AND wp.meta_value LIKE '%sosa%' 
ORDER BY wp.meta_value;

【讨论】：