In WPMU version 2.7, there are 9 global tables: blogs, blog_versions, registration_log, signups, site, sitecategories, sitemeta, usermeta, users. These 9 tables are fixed and serving for WPMU system globally. Every blog has its own 8 tables: comments, links, options, postmeta, posts, terms, term_relationships, term_taxonomy. These 8 tables are created over and over every new blog is created.

This designing is cool and useful from scalability view, especially for those big blogging service providers, wordpress.com is a good example. But WPMU uses only one database by default, it’s hard to manage the excessive tables in one database, and the performance should also not be good. OK, here comes HyperDB, which can solve this problem. Actually HyperDB is derived from the code using by wordpress.com.

Before starting installing and configuring, we need to define a rule for databases. In this post, the rule is:

• One database (wpmu_db0) for the global tables and the tables of first blog. It can be called global database.
• Additional 3 databases (wpmu_db1, wpmu_db2, wpmu_db3) for the tables of other blogs, each database serves 2 blogs.

Of course, you can define your own rules based-on your needs. It’s flexible.

We can start now. The first thing is to set up a standard WPMU using the global database in the installation wizard. After that, go to WordPress website and download HyperDB. The version I’m using is 2008-11-27. There are three files in HyperDB package:

• db.php, which needs to be uploaded to wp-content directory
• db-settings.php, which needs to be uploaded to the directory that holds wp-config.php
• readme.txt, oh, you know what it means

Then add the following lines near the top of wp-config.php

define('WPMU', true);
require('db-settings.php');

Then add the blow code at the bottom of db-settings.php

// a handy function for mapping blog tables to dataset
function add_blog_tables($ds, $blog_id){
  add_db_table($ds, 'wp_' . $blog_id . '_comments');
  add_db_table($ds, 'wp_' . $blog_id . '_links');
  add_db_table($ds, 'wp_' . $blog_id . '_options');
  add_db_table($ds, 'wp_' . $blog_id . '_postmeta');
  add_db_table($ds, 'wp_' . $blog_id . '_posts');
  add_db_table($ds, 'wp_' . $blog_id . '_terms');
  add_db_table($ds, 'wp_' . $blog_id . '_term_relationships');
  add_db_table($ds, 'wp_' . $blog_id . '_term_taxonomy');
}
 
// add databases
add_db_server('global', 0, 'mysql3326_1', 1, 1, 'localhost:3326', '', 'wpmu_db0', 'wpuser', 'thepwd');
add_db_server('s1', 0, 'mysql3326_2', 1, 1, 'localhost:3326', '', 'wpmu_db1', 'wpuser', 'thepwd');
add_db_server('s2', 0, 'mysql3306_1', 1, 1, 'localhost:3306', '', 'wpmu_db2', 'wpuser', 'thepwd');
add_db_server('s3', 0, 'mysql3306_2', 1, 1, 'localhost:3306', '', 'wpmu_db3', 'wpuser', 'thepwd');
 
// add global tables which are in global database
add_db_table('global',  'wp_blogs');
add_db_table('global', 'wp_blog_versions');
add_db_table('global', 'wp_registration_log');
add_db_table('global', 'wp_signups');
add_db_table('global', 'wp_site');
add_db_table('global', 'wp_sitecategories');
add_db_table('global', 'wp_sitemeta');
add_db_table('global', 'wp_usermeta');
 
// add the tables for the first blog (created during wpmu installation)
// the first blog's tables are in global database
// of course, you can move it to any database you want
add_blog_tables('global', 1);
 
$dbsnum=3; // 3 additional databases
$blogs_per_db=2; // each database serves 2 blogs
 
for($db_id=1; $db_id<=$dbsnum; $db_id++){
  $dataset = 's' . $db_id;
  $max = $db_id * $blogs_per_db + 1; // include
  $min = $max - $blogs_per_db + 1; // include
  for($blog_id=$min; $blog_id<=$max; $blog_id++){
    add_blog_tables($dataset, $blog_id);
  }
}

That’s it!

Wanna try WPMU on local machine? If you use localhost or 127.0.0.1 as the server address directly, you always get a message similar to the following:

Do not use an IP address (like 127.0.0.1) as your server address. Do not use a single word hostname like localhost.

That means a FQDN is needed, the good thing is that it’s easy to resolve domain names virtually locally. Open the hosts file:

• C:\WINDOWS\system32\drivers\etc\hosts (Windows)
• /etc/hosts (Linux)

Add or modify something, and make sure there is a line like the following in the file:

127.0.0.1    localhost hys.lan bloga.hys.lan blogb.hys.lan blogc.hys.lan blogd.hys.lan

Here, hys.lan is used to install WPMU, blog(a-d).hys.lan are addresses for testing, I’ll use these four to create weblogs.

Configuring Apache

Make sure two things:

• Apache is listening on port 80, because WPMU doesn’t support server address with port number.
• mod_rewrite is enabled.

Then adds a virtual host section:

<VirtualHost *:80>
  DocumentRoot /opt/wordpress-mu
  ServerName hys.lan
  ServerAlias *.hys.lan
  <Directory "/opt/wordpress-mu">
    AllowOverride FileInfo
    Order allow,deny
    Allow from all
  </Directory>
</VirtualHost>

Preparing Database

Create an empty database, and grant permissions to a database user.

mysql> create database wpmu_db;
mysql> grant all privileges on wpmu_db.* to wpuser@'%' identified by 'thepwd';
mysql> flush privileges;

Installing WPMU

It’s very easy to get WPMU up. Open your browser, and type the server address, in my case, it’s http://hys.lan. Provide the required information, and press the “Submit” button to go. Waiting for a while, WPMU is installed and runs successfully.

基于以上理由，我决定抛弃 WP 内置的 TinyMCE ，使用最新的 TinyMCE 2.0.9 来作为俺的 editor.

1 Disable WP built-in TinyMCE

登录 WP 控制台，然后进入 Options -> Writing ，在 Formatting 中清除对 “Users should use the visual rich editor by default” 项的选择。

进入 Users ，在 Personal Options 中清除对 “Use the visual rich editor when writing” 项的选择。

2 Download the latest TinyMCE

到其官方站下载最新版，我此时的是 2.0.9。

3 Install TinyMCE

解开下载包
$ unzip tinymce_2_0_9.zip
$ unzip tinymce_lpackage.zip （如果你也下载了语言包的话）

把 jscripts 目录下的 tiny_mce 复制到 $WP_HOME/wp-includes/js/ 下。其实可以复制到任意能通过 browser 访问的地方，但是为了看起来比较一致，我将它复制到了 WP 用来放 javascript 的地方。
$ cd tinymce/jscripts
$ cp -fr tiny_mce $WP_HOME/wp-includes/js/

改个名字，好区分这是我自己安装的
$ cd $WP_HOME/wp-includes/js/
$ mv tiny_mce tinymce209hys

4 Confiure TinyMCE

在 $WP_HOME/wp-includes/js/ 下新建一个文件 init_tinymce209hys.js ，同样，这个脚本文件可以放到任意能通过 browser 访问的地方，文件名也随便。

该文件是用来配置新安装的 TinyMCE 的，至于如何配置 TinyMCE ，可以访问其官方 WIKI 来获取帮助。以下是我的配置：

tinyMCE.init({
  mode : "exact",
  elements : "content",
  theme : "advanced",
  language : "zh_cn_utf8",
  width : "100%",
  height : "400",
  plugins : "paste,table",
  theme_advanced_buttons1 : "cut, copy, paste, pastetext, separator, fontselect, fontsizeselect, separator, bold, italic, underline, strikethrough, separator, bullist, numlist, separator, justifyleft, justifycenter, justifyright, separator, forecolor, backcolor, separator, link, unlink, separator, table, row_props, cell_props, separator, charmap, image, removeformat, code",
  theme_advanced_buttons2 : "",
  theme_advanced_toolbar_location : "top",
  theme_advanced_toolbar_align : "left",
  theme_advanced_statusbar_location : "none",
  theme_advanced_path : false,
  relative_urls : false,
  remove_script_host : false
});

5 Modify $WP_HOME/wp-admin/admin-header.php

将第49行

<?php if ( $editing && user_can_richedit() ) { ?>

修改为

<?php if ( $editing ) { ?>

即，去除对用户是否使用 rich editor 的判断。

将第50行

<script type="text/javascript" src="../wp-includes/js/tinymce/tiny_mce_gzip.php?ver=20051211"></script>

修改为

<script type="text/javascript" src="../wp-includes/js/tinymce209hys/tiny_mce.js"></script>
<script type="text/javascript" src="../wp-includes/js/init_tinymce209hys.js"></script>

完工！

附注：我的 WP 是 2.0.5 版。

类似这样的问题还不少，比如单引号也如此，相应地，我注销了第31、36行。

编辑 $WP_HOME/wp-config.php

若无此文件，就复制相同目录下的 wp-config-sample.php 新建一个。
在该文件中指定数据库名、用户名、密码、数据库服务器主机名或IP即可。很简单的。唯一需要指出的是，若你的 MySQL 不是监听默认的 3306 端口，那么在指定 DB_HOST 是需要指出其端口，比如：

define('DB_HOST', 'localhost:3366');

字符集问题

为了避免出现乱码现象，创建 MySQL 数据库时需要使用 utf8 作为默认字符集。

另外还需要修改 $WP_HOME/wp-includes/wp-db.php 文件，强制 WP 在连接数据库时使用 utf8
找到如下一行
$this->dbh = @mysql_connect($dbhost, $dbuser, $dbpassword);
应该是在第 43 行。
在该行下加一行
$this->query("set names 'utf8'");
即可。

控制板

当进入 WP 的控制板时，它会自动从 technorati.com, wordpress.org 上获取一些与 WP 有关的最新信息，这当然是很好的，但是因为从中国访问这两个网站的速度都不太理想，所以导致每次进入控制板时速度很慢。而且我们也并非每次进入控制板时都需要看有关 WP 的最新信息，再说了，哪会有那么多的 WP 相关信息更新啊。因此，为了速度计，我决定取消信息攫取。

打开 $WP_HOME/wp-admin/index.php
搜寻字符串 $rss = @fetch_rss
应该有三行，分别在 18, 129, 146.
把这三行注释掉即可。

好了，现在可以启动 WP 的安装向导了。Have fun!