带标签和 GROUP_CONCAT 的产品视图

Question

我在我的应用程序上使用 Sphinx 进行全文搜索。我使用 view 来过滤 products 表中的数据，并为该视图建立索引。现在，我在产品表下有一个硬编码字段及其相关标签，但这不太好，因为标签可能会发生变化，而且我每次都必须操作硬编码字段。

所以我想我可以使用 GROUP_CONCAT 创建视图，用如下语法列出所有相关标签：

SELECT p.id AS id, GROUP_CONCAT(t.tag SEPARATOR '|') AS tags,
UNIX_TIMESTAMP(p.created) AS created
FROM products p
INNER JOIN products_tags pt ON pt.product_id = p.id
INNER JOIN tags t ON t.id = pt.tag_id
AND p.deleted = 0
AND (p.images IS NOT NULL OR p.images <> '')
AND p.status LIKE 'listed'
GROUP BY p.id;

这个查询的问题是它需要很长时间才能运行。真的很慢。如果只检索一条记录，最多需要 5 秒。这是 EXPLAIN 输出：

1, SIMPLE, pt, ALL, , , , , 165029, Using temporary; Using filesort
1, SIMPLE, p, eq_ref, PRIMARY, PRIMARY, 4, trych_default.pt.product_id, 1, Using where
1, SIMPLE, t, eq_ref, PRIMARY, PRIMARY, 4, trych_default.pt.tag_id, 1, 

我想知道是否有任何方法可以改进查询，或者可能有更好的解决方案来解决我的问题。谢谢！

Answer 1

您可能缺少索引。使用以下架构，相同的查询命中每个表的索引：

CREATE TABLE `products` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `deleted` tinyint(1) unsigned NOT NULL DEFAULT '0',
  `status` varchar(255) NOT NULL DEFAULT 'listed',
  `images` varchar(255) DEFAULT NULL,
  `created` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `tags` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `tag` varchar(255) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `products_tags` (
  `product_id` int(11) NOT NULL,
  `tag_id` int(11) NOT NULL DEFAULT '0',
  PRIMARY KEY (`product_id`,`tag_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

以下是 EXPLAIN 查询的结果：

EXPLAIN SELECT p.id AS id, GROUP_CONCAT(t.tag SEPARATOR '|') AS tags,
UNIX_TIMESTAMP(p.created) AS created
FROM products p
INNER JOIN products_tags pt ON pt.product_id = p.id
INNER JOIN tags t ON t.id = pt.tag_id
WHERE p.deleted = 0
AND (p.images IS NOT NULL OR p.images <> '')
AND p.status LIKE 'listed'
GROUP BY p.id;

+----+-------------+-------+--------+---------------+---------+---------+----------------+------+-------------+
| id | select_type | table | type   | possible_keys | key     | key_len | ref            | rows | Extra       |
+----+-------------+-------+--------+---------------+---------+---------+----------------+------+-------------+
|  1 | SIMPLE      | p     | index  | PRIMARY       | PRIMARY | 4       | NULL           |    1 | Using where |
|  1 | SIMPLE      | pt    | ref    | PRIMARY       | PRIMARY | 4       | test.p.id      |    1 | Using index |
|  1 | SIMPLE      | t     | eq_ref | PRIMARY       | PRIMARY | 4       | test.pt.tag_id |    1 |             |
+----+-------------+-------+--------+---------------+---------+---------+----------------+------+-------------+
3 rows in set (0.00 sec)