Is there a simpler way to achieve this style of user messaging?

Question

I have created a messaging system for users, it allows them to send a message to another user. If it is the first time they have spoken then a new conversation is initiated,

Answer 1

How to create a fast Facebook-like messages system. tested and widely used by Arutz Sheva users - http://www.inn.co.il (Hebrew).

1. create a "topic" (conversation) table:

     CREATE TABLE pb_topics (
     t_id int(11) NOT NULL AUTO_INCREMENT,
     t_last int(11) NOT NULL DEFAULT '0',
     t_user int(11) NOT NULL DEFAULT '0',
     PRIMARY KEY (t_id),
     KEY last (t_last)
   ) ENGINE=InnoDB AUTO_INCREMENT=137106342 DEFAULT CHARSET=utf8

2. create link between user and conversation:

       CREATE TABLE pb_links (
     l_id int(11) NOT NULL AUTO_INCREMENT,
     l_user int(11) NOT NULL DEFAULT '0',
     l_new int(11) NOT NULL DEFAULT '0',
     l_topic int(11) NOT NULL DEFAULT '0',
     l_visible int(11) NOT NULL DEFAULT '1',
     l_bcc int(11) NOT NULL DEFAULT '0',
     PRIMARY KEY (l_id) USING BTREE,
     UNIQUE KEY topic-user (l_topic,l_user),
     KEY user-topicnew (l_user,l_new,l_topic) USING BTREE,
     KEY user-topic (l_user,l_visible,l_topic) USING BTREE
   ) ENGINE=InnoDB AUTO_INCREMENT=64750078 DEFAULT CHARSET=utf8

3. create a message

       CREATE TABLE pb_messages (
     m_id int(11) NOT NULL AUTO_INCREMENT,
     m_from int(11) NOT NULL,
     m_date datetime NOT NULL DEFAULT '1987-11-13 00:00:00',
     m_title varchar(75) NOT NULL,
     m_content mediumtext NOT NULL,
     m_topic int(11) NOT NULL,
     PRIMARY KEY (m_id),
     KEY date_topic (m_date,m_topic),
     KEY topic_date_from (m_topic,m_date,m_from)
   ) ENGINE=InnoDB 

A conversation can be with 2 or more friends (BCC was added like email, but you can skip it).

Insert a new message: 1. Create new topic 2. Create Links for users (from/to) 3. Add Message (4. Update users cache table - user have messages)

Add Message to topic: Add Message

Select folder:

select 
     z.*, group_concat(u_name) as users_name from
         (select max(m_id) as m_id, m_topic as t_id,  m_From, m_title,m_date, l_new 
              from pb_links as l1, pb_messages 
              where l1.l_user=  and m_from < If(inbox, "<>", "=") > and m_topic=l_topic and l1.l_visible=1 
               group by m_topic order by m_id desc limit " & iPage * 35 & ",35) z
           left join  pb_links l2  on (l2.l_topic=t_id)
           left join  users  on (l_user=u_id and l_bcc=0 and l_user)  
            group by l_topic order by m_date desc;

In details:

The first is the inner select - this is the fastest way (I was check about 7 other options, checked also in Percona/MariaDB versions) to get all messages, and get also the last message to display in the list. Also look in the inner IF - in inbox, the last message is anyone but not me, and In outbox - the opposite. LIMIT used for paging.

The outer one used to add user list (just name comma name string) and more information for only one message per topic, and after paging (I need to add user list just to the 35-per-page messages, and not for all my large history).

Also, I wrote in hebrew here: http://blogs.microsoft.co.il/blogs/moshel/archive/2010/08/12/quot-x-quot.aspx to create a simple cache table, and forbid the workload of select count from busy message table.