普遍缓存技术
数据缓存：这里所说的数据缓存是指数据库查询缓存，每次访问页面的时候,都会先检测相应的缓存数据是否存在，如果不存在，就连接数据库，得到数据， 并把查询结果序列化后保存到文件中，以后同样的查询结果就直接从缓存表或文件中获得。
用的最广的例子看Discuz的搜索功能，把结果ID缓存到一个表中，下次搜索相同关键字时先搜索缓存表。
举个常用的方法，多表关联的时候，把附表中的内容生成数组保存到主表的一个字段中，需要的时候数组分解一下，这样的好处是只读一个表，坏处就是两个 数据同步会多不少步骤，数据库永远是瓶颈，用硬盘换速度，是这个的关键点。
页面缓存：
每次访问页面的时候，都会先检测相应的缓存页面文件是否存在，如果不存在，就连接数据库，得到数据，显示页面并同时生成缓存页面文件，这样下次访问 的时候页面文件就发挥作用了。(模板引擎和网上常见的一些缓存类通常有此功能)
时间触发缓存：
检查文件是否存在并且时间戳小于设置的过期时间,如果文件修改的时间戳比当前时间戳减去过期时间戳大，那么就用缓存，否则更新缓存。
内容触发缓存：
当插入数据或更新数据时，强制更新缓存。
静态缓存：
这里所说的静态缓存是指静态化，直接生成HTML或xml等文本文件，有更新的时候重生成一次，适合于不太变化的页面，这就不说了。
以上内容是代码级的解决方案，我直接CP别的框架，也懒得改，内容都差不多，很容易就做到，而且会几种方式一起用，但下面的内容是服务器端的缓存方 案，非代码级的，要有多方的合作才能做到
内存缓存:
Memcached是高性能的，分布式的内存对象缓存系统，用于在动态应用中减少数据库负载，提升访问速度。
这里说下Memcached的例子：
<ol class="dp-c"> <li class="alt"><span><span><?php </span></span></span></li> <li> <span class="vars">$memcache</span><span> = </span><span class="keyword">new</span><span> Memcache; </span> </li> <li class="alt"> <span class="vars">$memcache</span><span>->connect(‘localhost’, 11211) </span><span class="keyword">or</span><span> </span><span class="keyword">die</span><span> (“Could not connect”); </span> </li> <li> <span class="vars">$version</span><span> = </span><span class="vars">$memcache</span><span>->getVersion(); </span> </li> <li class="alt"> <span class="func">echo</span><span> “Server’s version: “.</span><span class="vars">$version</span><span>.”n”; </span> </li> <li> <span class="vars">$tmp_object</span><span> = </span><span class="keyword">new</span><span> stdClass; </span> </li> <li class="alt"> <span class="vars">$tmp_object</span><span>->str_attr = ‘test’; </span> </li> <li> <span class="vars">$tmp_object</span><span>->int_attr = 123; </span> </li> <li class="alt"> <span class="vars">$memcache</span><span>->set(‘key’, </span><span class="vars">$tmp_object</span><span>, false, 10) </span><span class="keyword">or</span><span> </span><span class="keyword">die</span><span> (“Failed to save data at the server”); </span> </li> <li> <span class="func">echo</span><span> “Store data in the cache (data will expire in 10 seconds)n”; </span> </li> <li class="alt"> <span class="vars">$get_result</span><span> = </span><span class="vars">$memcache</span><span>->get(‘key’); </span> </li> <li> <span class="func">echo</span><span> “Data from the cache:n”; </span> </li> <li class="alt"> <span>var_dump(</span><span class="vars">$get_result</span><span>); </span> </li> <li><span>?> </span></li> </ol>
读库的例子：
<ol class="dp-c">
<li class="alt"><span><span><?php </span></span></span></li>
<li>
<span class="vars">$sql</span><span> = ‘SELECT * FROM users’; </span>
</li>
<li class="alt">
<span class="vars">$key</span><span> = md5(</span><span class="vars">$sql</span><span>); </span><span class="comment">//memcached 对象标识符 </span><span> </span>
</li>
<li>
<span class="keyword">if</span><span> ( !(</span><span class="vars">$datas</span><span> = </span><span class="vars">$mc</span><span>->get(</span><span class="vars">$key</span><span>)) ) { </span>
</li>
<li class="alt">
<span class="comment">// 在 memcached 中未获取到缓存数据，则使用数据库查询获取记录集。 </span><span> </span>
</li>
<li>
<span class="func">echo</span><span> “n”.</span><span class="func">str_pad</span><span>(‘Read datas from MySQL.’, 60, ‘_’).”n”; </span>
</li>
<li class="alt">
<span class="vars">$conn</span><span> = mysql_connect(‘localhost’, ‘test’, ‘test’); </span>
</li>
<li><span>mysql_select_db(‘test’); </span></li>
<li class="alt">
<span class="vars">$result</span><span> = mysql_query(</span><span class="vars">$sql</span><span>); </span>
</li>
<li>
<span class="keyword">while</span><span> (</span><span class="vars">$row</span><span> = mysql_fetch_object(</span><span class="vars">$result</span><span>)) </span>
</li>
<li class="alt">
<span class="vars">$datas</span><span>[] = </span><span class="vars">$row</span><span>; </span>
</li>
<li>
<span class="comment">// 将数据库中获取到的结果集数据保存到 memcached 中，以供下次访问时使用。 </span><span> </span>
</li>
<li class="alt">
<span class="vars">$mc</span><span>->add(</span><span class="vars">$key</span><span>, </span><span class="vars">$datas</span><span>); </span>
</li>
<li>
<span>} </span><span class="keyword">else</span><span> { </span>
</li>
<li class="alt">
<span class="func">echo</span><span> “n”.</span><span class="func">str_pad</span><span>(‘Read datas from memcached.’, 60, ‘_’).”n”; </span>
</li>
<li><span>} </span></li>
<li class="alt">
<span>var_dump(</span><span class="vars">$datas</span><span>); </span>
</li>
<li><span>?> </span></li>
</ol>PHP的缓冲器：
有eaccelerator， apc， PHPa，xcache，这个这个就不说了吧，搜索一堆一堆的，自己看啦，知道有这玩意就OK
MYSQL缓存：
这也算非代码级的，经典的数据库就是用的这种方式，看下面的运行时间，0.09xxx之类的
我贴段根据蓝色那家伙修改后部分my.ini 吧，2G的MYISAM表可以在0.05S左右，据说他前后改了有快一年
<ol class="dp-c"> <li class="alt"><span><span>[client] </span></span></li> <li><span>…… </span></li> <li class="alt"> <span class="keyword">default</span><span>-character-set=gbk </span> </li> <li> <span class="keyword">default</span><span>-storage-engine=MYISAM </span> </li> <li class="alt"><span>max_connections=600 </span></li> <li><span>max_connect_errors=500 </span></li> <li class="alt"><span>back_log=200 </span></li> <li><span>interactive_timeout=7200 </span></li> <li class="alt"><span>query_cache_size=64M </span></li> <li><span>…… </span></li> <li class="alt"><span>table_cache=512 </span></li> <li><span>…… </span></li> <li class="alt"><span>myisam_max_sort_file_size=100G </span></li> <li><span>myisam_max_extra_sort_file_size=100G </span></li> <li class="alt"><span>myisam_sort_buffer_size=128M </span></li> <li><span>key_buffer_size=1024M </span></li> <li class="alt"><span>read_buffer_size=512M </span></li> <li><span>…… </span></li> <li class="alt"><span>thread_concurrency=8 </span></li> </ol>
基于反向代理的Web缓存:
如Nginx，SQUID，mod_PRoxy(apache2以上又分为mod_proxy和mod_cache)
NGINX的例子
<ol class="dp-c">
<li class="alt"><span><span><nginx.conf> </nginx.conf></span></span></li>
<li><span>#user nobody; </span></li>
<li class="alt"><span>worker_processes 4; </span></li>
<li>
<span class="func">error_log</span><span> logs/error.log crit; </span>
</li>
<li class="alt"><span>pid logs/nginx.pid; </span></li>
<li><span>worker_rlimit_nofile 10240; </span></li>
<li class="alt"><span>events { </span></li>
<li>
<span class="keyword">use</span><span> epoll; </span>
</li>
<li class="alt"><span>worker_connections 51200; </span></li>
<li><span>} </span></li>
<li class="alt"><span>http { </span></li>
<li>
<span class="keyword">include</span><span> mime.types; </span>
</li>
<li class="alt"><span>default_type application/octet-stream; </span></li>
<li><span>sendfile on; </span></li>
<li class="alt"><span>keepalive_timeout 65; </span></li>
<li><span>tcp_nodelay on; </span></li>
<li class="alt"><span># server pool </span></li>
<li><span>upstream bspfrontsvr { </span></li>
<li class="alt"><span>server 10.10.10.224:80 weight=1; </span></li>
<li><span>server 10.10.10.221:80 weight=1; </span></li>
<li class="alt"><span>} </span></li>
<li><span> </span></li>
<li class="alt"><span>upstream bspimgsvr { </span></li>
<li><span>server 10.10.10.201:80 weight=1; </span></li>
<li class="alt"><span>} </span></li>
<li><span> </span></li>
<li class="alt"><span>upstream bspstylesvr { </span></li>
<li><span>server 10.10.10.202:80 weight=1; </span></li>
<li class="alt"><span>} </span></li>
<li><span> </span></li>
<li class="alt"><span>upstream bsphelpsvr { </span></li>
<li><span>server 10.10.10.204:80 weight=1; </span></li>
<li class="alt"><span>} </span></li>
<li><span> </span></li>
<li class="alt"><span>upstream bspwsisvr { </span></li>
<li><span>server 10.10.10.203:80 weight=1; </span></li>
<li class="alt"><span>} </span></li>
<li><span> </span></li>
<li class="alt"><span>upstream bspadminsvr { </span></li>
<li><span>server 10.10.10.222:80 weight=1; </span></li>
<li class="alt"><span>} </span></li>
<li><span> </span></li>
<li class="alt"><span>upstream bspbuyersvr { </span></li>
<li><span>server 10.10.10.223:80 weight=1; </span></li>
<li class="alt"><span>} </span></li>
<li><span> </span></li>
<li class="alt"><span>upstream bspsellersvr { </span></li>
<li><span>server 10.10.10.225:80 weight=1; </span></li>
<li class="alt"><span>} </span></li>
<li><span>upstream bsploginsvr { </span></li>
<li class="alt"><span>server 10.10.10.220:443 weight=1; </span></li>
<li><span>} </span></li>
<li class="alt"><span>upstream bspregistersvr { </span></li>
<li><span>server 10.10.10.220:80 weight=1; </span></li>
<li class="alt"><span>} </span></li>
<li>
<span>log_format test_com ‘</span><span class="vars">$remote_addr</span><span> – </span><span class="vars">$remote_user</span><span> [</span><span class="vars">$time_local</span><span>] “</span><span class="vars">$request</span><span>” ‘ </span>
</li>
<li class="alt">
<span>‘</span><span class="vars">$status</span><span> </span><span class="vars">$body_bytes_sent</span><span> “</span><span class="vars">$http_referer</span><span>” “</span><span class="vars">$http_user_agent</span><span>” ‘; </span>
</li>
<li><span>#——————————————————————– </span></li>
<li class="alt"><span>#img.test.com </span></li>
<li><span>server { </span></li>
<li class="alt"><span>listen 10.10.10.230:80; </span></li>
<li><span>server_name img.test.com; </span></li>
<li class="alt"><span>location / { </span></li>
<li>
<span>proxy_pass http:</span><span class="comment">//bspimgsvr; </span><span> </span>
</li>
<li class="alt">
<span class="keyword">include</span><span> proxy_setting.conf; </span>
</li>
<li><span>} </span></li>
<li class="alt"><span>access_log logs/img.log test_com; </span></li>
<li><span>} </span></li>
<li class="alt"><span> </span></li>
<li><span>#style.test.com </span></li>
<li class="alt"><span>server { </span></li>
<li><span>listen 10.10.10.230:80; </span></li>
<li class="alt"><span>server_name style.test.com; </span></li>
<li><span>location / { </span></li>
<li class="alt">
<span>proxy_pass http:</span><span class="comment">//bspstylesvr; </span><span> </span>
</li>
<li>
<span class="keyword">include</span><span> proxy_setting.conf; </span>
</li>
<li class="alt"><span>} </span></li>
<li><span>access_log logs/style.log test_com; </span></li>
<li class="alt"><span>} </span></li>
<li><span> </span></li>
<li class="alt"><span>#help.test.com </span></li>
<li><span>server { </span></li>
<li class="alt"><span>listen 10.10.10.230:80; </span></li>
<li><span>server_name help.test.com; </span></li>
<li class="alt"><span>location / { </span></li>
<li>
<span>proxy_pass http:</span><span class="comment">//bsphelpsvr; </span><span> </span>
</li>
<li class="alt">
<span class="keyword">include</span><span> proxy_setting.conf; </span>
</li>
<li><span>} </span></li>
<li class="alt"><span>access_log logs/help.log test_com; </span></li>
<li><span>} </span></li>
<li class="alt"><span> </span></li>
<li><span>#admin.test.com </span></li>
<li class="alt"><span>server { </span></li>
<li><span>listen 10.10.10.230:80; </span></li>
<li class="alt"><span>server_name admin.test.com; </span></li>
<li><span>location / { </span></li>
<li class="alt">
<span>proxy_pass http:</span><span class="comment">//bspadminsvr; </span><span> </span>
</li>
<li>
<span class="keyword">include</span><span> proxy_setting.conf; </span>
</li>
<li class="alt"><span>} </span></li>
<li><span>access_log logs/admin.log test_com; </span></li>
<li class="alt"><span>} </span></li>
<li><span> </span></li>
<li class="alt"><span>#buyer.test.com </span></li>
<li><span>server { </span></li>
<li class="alt"><span>listen 10.10.10.230:80; </span></li>
<li><span>server_name buyer.test.com; </span></li>
<li class="alt"><span>location / { </span></li>
<li>
<span>proxy_pass http:</span><span class="comment">//bspbuyersvr; </span><span> </span>
</li>
<li class="alt">
<span class="keyword">include</span><span> proxy_setting.conf; </span>
</li>
<li><span>} </span></li>
<li class="alt"><span>access_log logs/buyer.log test_com; </span></li>
<li><span>} </span></li>
<li class="alt"><span> </span></li>
<li><span>#seller.test.com </span></li>
<li class="alt"><span>server { </span></li>
<li><span>listen 10.10.10.230:80; </span></li>
<li class="alt"><span>server_name seller.test.com; </span></li>
<li><span>location / { </span></li>
<li class="alt">
<span>proxy_pass http:</span><span class="comment">//bspsellersvr; </span><span> </span>
</li>
<li>
<span class="keyword">include</span><span> proxy_setting.conf; </span>
</li>
<li class="alt"><span>} </span></li>
<li><span>access_log logs/seller.log test_com; </span></li>
<li class="alt"><span>} </span></li>
<li><span>#wsi.test.com </span></li>
<li class="alt"><span>server { </span></li>
<li><span>listen 10.10.10.230:80; </span></li>
<li class="alt"><span>server_name wsi.test.com; </span></li>
<li><span>location / { </span></li>
<li class="alt">
<span>proxy_pass http:</span><span class="comment">//bspwsisvr; </span><span> </span>
</li>
<li>
<span class="keyword">include</span><span> proxy_setting.conf; </span>
</li>
<li class="alt"><span>} </span></li>
<li><span>access_log logs/wsi.log test_com; </span></li>
<li class="alt"><span>} </span></li>
<li><span>#www.test.com </span></li>
<li class="alt"><span>server { </span></li>
<li><span>listen 10.10.10.230:80; </span></li>
<li class="alt"><span>server_name www.test.com *.test.com; </span></li>
<li><span>location ~ ^/NginxStatus/ { </span></li>
<li class="alt"><span>stub_status on; </span></li>
<li><span>access_log off; </span></li>
<li class="alt"><span>} </span></li>
<li><span>location / { </span></li>
<li class="alt">
<span>proxy_pass http:</span><span class="comment">//bspfrontsvr; </span><span> </span>
</li>
<li>
<span class="keyword">include</span><span> proxy_setting.conf; </span>
</li>
<li class="alt"><span>} </span></li>
<li><span>access_log logs/www.log test_com; </span></li>
<li class="alt"><span>error_page 500 502 503 504 /50x.html; </span></li>
<li><span>location = /50x.html { </span></li>
<li class="alt"><span>root html; </span></li>
<li><span>} </span></li>
<li class="alt"><span>} </span></li>
<li><span>#login.test.com </span></li>
<li class="alt"><span>server { </span></li>
<li><span>listen 10.10.10.230:443; </span></li>
<li class="alt"><span>server_name login.test.com; </span></li>
<li><span>ssl on; </span></li>
<li class="alt"><span>ssl_certificate cert.pem; </span></li>
<li><span>ssl_certificate_key cert.key; </span></li>
<li class="alt"><span>ssl_session_timeout 5m; </span></li>
<li><span>ssl_protocols SSLv2 SSLv3 TLSv1; </span></li>
<li class="alt">
<span>ssl_ciphers ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+</span><span class="func">EXP</span><span>; </span>
</li>
<li><span>ssl_prefer_server_ciphers on; </span></li>
<li class="alt"><span>location / { </span></li>
<li>
<span>proxy_pass https:</span><span class="comment">//bsploginsvr; </span><span> </span>
</li>
<li class="alt">
<span class="keyword">include</span><span> proxy_setting.conf; </span>
</li>
<li><span>} </span></li>
<li class="alt"><span>access_log logs/login.log test_com; </span></li>
<li><span>} </span></li>
<li class="alt">
<span>#login.test.com </span><span class="keyword">for</span><span> register </span>
</li>
<li><span>server { </span></li>
<li class="alt"><span>listen 10.10.10.230:80; </span></li>
<li><span>server_name login.test.com; </span></li>
<li class="alt"><span>location / { </span></li>
<li>
<span>proxy_pass http:</span><span class="comment">//bspregistersvr; </span><span> </span>
</li>
<li class="alt">
<span class="keyword">include</span><span> proxy_setting.conf; </span>
</li>
<li><span>} </span></li>
<li class="alt"><span>access_log logs/register.log test_com; </span></li>
<li><span>} </span></li>
<li class="alt"><span> </span></li>
<li><span>} </span></li>
<li class="alt"><span><conf> </conf></span></li>
<li><span>proxy_redirect off; </span></li>
<li class="alt">
<span>proxy_set_header Host </span><span class="vars">$host</span><span>; </span>
</li>
<li>
<span>proxy_set_header X-Real-IP </span><span class="vars">$remote_addr</span><span>; </span>
</li>
<li class="alt">
<span>proxy_set_header X-Forwarded-For </span><span class="vars">$proxy_add_x_forwarded_for</span><span>; </span>
</li>
<li><span>client_max_body_size 10m; </span></li>
<li class="alt"><span>client_body_buffer_size 128k; </span></li>
<li><span>proxy_connect_timeout 90; </span></li>
<li class="alt"><span>proxy_send_timeout 90; </span></li>
<li><span>proxy_read_timeout 90; </span></li>
<li class="alt"><span>proxy_buffer_size 4k; </span></li>
<li><span>proxy_buffers 4 32k; </span></li>
<li class="alt"><span>proxy_busy_buffers_size 64k; </span></li>
<li><span>proxy_temp_file_write_size 64k; </span></li>
<li class="alt"><span>mod_proxy的例子： </span></li>
<li><span> </span></li>
<li class="alt"><span><virtualhost> </virtualhost></span></li>
<li><span>ServerName www.zxsv.com </span></li>
<li class="alt"><span>ServerAdmin admin@zxsv.com </span></li>
<li><span># reverse proxy setting </span></li>
<li class="alt">
<span>ProxyPass / http:</span><span class="comment">//www.zxsv.com:8080/ </span><span> </span>
</li>
<li>
<span>ProxyPassReverse / http:</span><span class="comment">//www.zxsv.com:8080/ </span><span> </span>
</li>
<li class="alt"><span># cache dir root </span></li>
<li>
<span>CacheRoot “/</span><span class="keyword">var</span><span>/www/proxy” </span>
</li>
<li class="alt"><span># max cache storage </span></li>
<li><span>CacheSize 50000000 </span></li>
<li class="alt"><span># hour: every 4 hour </span></li>
<li><span>CacheGcInterval 4 </span></li>
<li class="alt"><span># max page expire time: hour </span></li>
<li><span>CacheMaxExpire 240 </span></li>
<li class="alt"><span># Expire time = (now – last_modified) * CacheLastModifiedFactor </span></li>
<li><span>CacheLastModifiedFactor 0.1 </span></li>
<li class="alt"><span># defalt expire tag: hour </span></li>
<li><span>CacheDefaultExpire 1 </span></li>
<li class="alt"><span># force complete after precent of content retrived: 60-90% </span></li>
<li><span>CacheForceCompletion 80 </span></li>
<li class="alt"><span>CustomLog /usr/local/apache/logs/dev_access_log combined </span></li>
<li><span> </span></li>
</ol>而SQUID的例子我就不说明了，这方面网上有写的太多，大家自己搜索一下
DNS轮询：
BIND是一款开放源码的DNS服务器软件，这个要说起来就大了，自己搜索去，大家知道有这个东西就行了。
我知道的有chinacache 等大站就是这样做的，说简单点就是多服务器啦，把同一个页面或文件缓存到不同的服务器上，按南北自动解析到相关的服务器中。
http://www.cnblogs.com/cnblogs20112011/archive/2011/01/27/1946286.html
Datenbank drei Paradigmen
So löschen Sie eine Datenbank
So stellen Sie eine Verbindung zur Datenbank in VB her
So öffnen Sie eine PHP-Datei
MySQL-Datenbank wiederherstellen
So stellen Sie eine Verbindung zum Zugriff auf die Datenbank in VB her
So entfernen Sie die ersten paar Elemente eines Arrays in PHP
Was tun, wenn die PHP-Deserialisierung fehlschlägt?
![[Web-Frontend] Node.js-Schnellstart](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
