问题 何时使用memcached

我有点了解memcached的工作原理。您使用它来存储数据块以提高站点性能。当你想要检索一些数据时，先检查它是否在memcached中，如果是，则检索它，否则检查数据库/文件系统等。

我只是不知道如何/何时使用它？什么是好机会？

我有以下表格：

作者：

id username电子邮件密码salt     email_salt email_verified     IP地址

Author_threads：

thread_id，author_id

线：

id，title，content，created

标签：

id，名字

Thread_tags：

tad_id，thread_id

我想选择最新的30个主题，他们的作者和所有标签。这是我使用的SQL语句：

       SELECT thread.title, thread.id as thread_id,
       thread.content, author.username, author.id as author_id,
       GROUP_CONCAT(DISTINCT tag.name ORDER BY tag.name DESC SEPARATOR ',') AS tags
       FROM thread 
       JOIN thread_tags ON thread.id = thread_tags.thread_id
       JOIN tag ON thread_tags.tag_id = tag.id

       JOIN author_threads ON thread.id = author_threads.thread_id
       JOIN author ON author_threads.author_id = author.id

       GROUP BY thread.id DESC
       LIMIT 0, 30

这是我使用的PHP：

function get_latest_threads($link, $start)
{

   $start = minimal_int($start);

   $threads = sql_select($link, "SELECT thread.title, thread.id as thread_id,
                                 thread.content, author.username, author.id as author_id,
                                 GROUP_CONCAT(DISTINCT tag.name ORDER BY tag.name DESC SEPARATOR ',') AS tags
                                 FROM thread 
                                 JOIN thread_tags ON thread.id = thread_tags.thread_id
                                 JOIN tag ON thread_tags.tag_id = tag.id

                                 JOIN author_threads ON thread.id = author_threads.thread_id
                                 JOIN author ON author_threads.author_id = author.id

                                 GROUP BY thread.id DESC
                                 LIMIT $start, 30"  # I only want to retrieve 30 records each time
                        );

   return $threads;

}

memcached在哪里/如何使用？