在你回答这个问题之前，我从来没有开发过任何流行到足以达到高服务器负载的东西。请把我当作(唉)一个刚刚登陆地球的外星人，尽管我知道PHP和一些优化技术。
我正在开发一个PHP工具，可以获得相当多的用户，如果它是正确的。然而，虽然我完全有能力开发程序，但当涉及到制作可以处理巨大流量的东西时，我几乎一无所知。所以这里有一些关于它的问题(也可以把这个问题变成一个资源线程)。
数据库
At the moment I plan to use the MySQLi features in PHP5. However how should I setup the databases in relation to users and content? Do I actually need multiple databases? At the moment everything's jumbled into one database - although I've been considering spreading user data to one, actual content to another and finally core site content (template masters etc.) to another. My reasoning behind this is that sending queries to different databases will ease up the load on them as one database = 3 load sources. Also would this still be effective if they were all on the same server?
缓存
我有一个用于构建页面和交换变量的模板系统。主模板存储在数据库中，每当一个模板被调用时，它的缓存副本(html文档)就会被调用。目前，我在这些模板中有两种类型的变量-静态变量和动态变量。静态变量通常是像页面名称，网站的名称-不经常改变的东西;动态变量是在每次页面加载时改变的东西。
我的问题是:
比如说我对不同的文章有评论。这是一个更好的解决方案:存储简单的注释模板，并在每次页面加载时呈现注释(来自DB调用)，或者将注释页面的缓存副本存储为html页面——每次添加/编辑/删除注释时，页面都会被重新检索。
最后
有人有任何提示/指针运行一个高负载的PHP网站。我很确定这是一种可行的语言——Facebook和Yahoo!优先考虑——但有什么经验是我应该注意的吗?
第一个问题是，你真正期望它有多大?你们计划在基础设施上投资多少?既然你觉得有必要在这里问这个问题，我猜你希望从有限的预算开始。
Performance is irrelevant if the site is not available. And for availability you need horizontal scaling. The minimum you can sensibly get away with is 2 servers, both running apache, php and mysql. Set up one DBMS as a slave to the other. Do all the writes on the master, and all the reads on the local database (whatever that is) - unless for some reason you need to read back the data you've just read (use master). Make sure you've got the machinery in place to automatically promote the slave and fence the master. Use round-robin DNS for the webserver addresses to give more affinity for the slave node.
在这个阶段，在不同的数据库节点上划分你的数据是一个非常糟糕的主意——然而，你可能会考虑在同一台服务器上的不同数据库上划分数据(当你超越facebook时，这将有助于跨节点划分)。
一定要确保你有适当的监控和数据分析工具来衡量你的网站性能和识别瓶颈。大多数性能问题都可以通过编写更好的SQL /修复数据库模式来解决。
将模板缓存保存在数据库上是一个愚蠢的想法——数据库应该是结构化数据的中央公共存储库。将你的模板缓存保存在你的web服务器的本地文件系统中——这样会更快，也不会降低你对数据库的访问速度。
使用操作码缓存。
花大量的时间研究你的网站和它的日志，了解为什么它运行得这么慢。
将尽可能多的缓存推到客户端。
使用mod_gzip可以压缩所有内容。
C.
看来我错了。MySQLi仍在开发中。但是根据这篇文章，PDO_MySQL现在由MySQL团队贡献。摘自文章:
The MySQL Improved Extension - mysqli
- is the flagship. It supports all features of the MySQL Server including
Charsets, Prepared Statements and
Stored Procedures. The driver offers a
hybrid API: you can use a procedural
or object-oriented programming style
based on your preference. mysqli comes
with PHP 5 and up. Note that the End
of life for PHP 4 is 2008-08-08.
The PHP Data Objects (PDO) are a
database access abstraction layer. PDO
allows you to use the same API calls
for various databases. PDO does not
offer any degree of SQL abstraction.
PDO_MYSQL is a MySQL driver for PDO.
PDO_MYSQL comes with PHP 5. As of PHP
5.3 MySQL developers actively contribute to it. The PDO benefit of a
unified API comes at the price that
MySQL specific features, for example
multiple statements, are not fully
supported through the unified API.
Please stop using the first MySQL
driver for PHP ever published:
ext/mysql. Since the introduction of
the MySQL Improved Extension - mysqli
- in 2004 with PHP 5 there is no reason to still use the oldest driver
around. ext/mysql does not support
Charsets, Prepared Statements and
Stored Procedures. It is limited to
the feature set of MySQL 4.0. Note
that the Extended Support for MySQL
4.0 ends at 2008-12-31. Don't limit yourself to the feature set of such
old software! Upgrade to mysqli, see
also Converting_to_MySQLi. mysql is in
maintenance only mode from our point
of view.
对我来说，这篇文章似乎偏向MySQLi。我想我偏向于PDO。
我真的很喜欢PDO胜过MySQLi。这对我来说很简单。这个API更接近于我编写的其他语言。OO数据库接口似乎工作得更好。
我还没有遇到过任何PDO无法提供的MySQL特性。如果有的话，我才会惊讶呢。
