Question

我有8张桌子：

users:
  uid
users_removed:
  uid
messages:
  mid
  uid FK users (uid)
messages_removed:
  mid
  uid
comments:
  cid
  mid FK messages (mid)
comments_removed:
  cid
  mid
files:
  fid
  mid FK messages (mid)
files_removed:
  fid
  mid

当我从表“users”中删除记录时，我想将其移至table users_removed（在从用户删除之前）。我还想要将所有相应的消息（以及文件和注释）移动到* _removed表。

我使用了触发器：

CREATE TRIGGER delete_user BEFORE DELETE ON users
    FOR EACH ROW BEGIN
        INSERT IGNORE INTO users_removed
            SELECT * FROM users WHERE uid = OLD.uid;
        DELETE FROM messages WHERE OLD.uid in (owner_id, author_id);
    END
|

CREATE TRIGGER delete_message BEFORE DELETE ON messages
    FOR EACH ROW BEGIN
        INSERT IGNORE INTO messages_removed
            SELECT * FROM messages WHERE mid = OLD.mid;
        DELETE FROM comments WHERE mid = OLD.mid;
        DELETE FROM files WHERE mid = OLD.mid;
    END
|

CREATE TRIGGER delete_comment BEFORE DELETE ON comments
    FOR EACH ROW BEGIN
        INSERT IGNORE INTO comments_removed
            SELECT * FROM comments WHERE cid = OLD.cid;
    END
|

CREATE TRIGGER delete_file BEFORE DELETE ON files
    FOR EACH ROW BEGIN
        INSERT IGNORE INTO files_removed
            SELECT * FROM files WHERE fid = OLD.fid;
    END
|

但是＆gt;它的工作速度非常慢50k用户，＆gt; 1m消息，评论和文件。

有没有快速的方法呢？

Answer 1

没有快速的方法可以做到这一点。假设您正在使用InnoDB，您必须编写一个表条目，删除一个表条目引用，然后InnoDB进行第二次清理运行以实际摆脱它（删除是昂贵的）。然后，随着时间的推移删除更多用户，在数据库中出现这些漏洞几乎肯定会最终损害性能。
如果您要保存用户信息，为什么不直接使用enum（true，false）向名为“active”的users表添加一列？

如何使用其他连接表中的记录存档记录？

1 个答案: