用mysql触发器自动更新memcache的实现代码

mysql 5.1支持触发器以及自定义函数接口(UDF)的特性，如果配合libmemcache以及Memcached Functions for MySQL，就能够实现memcache的自动更新。简单记录一下安装测试步骤。

安装步骤

• 安装memcached,这个步骤很简单，随处可见
• 安装mysql server 5.1RC，安装办法也很大众，不废话了
• 编译libmemcached，解压后安装即可
  ./configure; make; make install
• 编译Memcached Functions for MySQL，在http://download.tangent.org/找一个最新的版本下载就是，
  ./configure --with-mysql=/usr/local/mysql/bin/mysql_config --libdir=/usr/local/mysql/lib/mysql/
make
make install

接下来有两个办法让Memcached Functions for MySQL在mysql中生效
• 在mysql的shell中执行memcached_functions_mysql源码目录下的sql/install_functions.sql，这会把memcache function作为UDF加入mysql
• 运行memcached_functions_mysql源码目录下的utils/install.pl，这是一个perl脚本，作用同上一条

测试memcache function
以下测试脚本摘自memcached_functions_mysql的源码目录，有兴趣可以试试

drop table if exists urls;
create table urls (
id int(3) not null,
url varchar(64) not null default '',
primary key (id)
);
select memc_servers_set('localhost:11211');
select memc_set('urls:sequence', 0);
DELIMITER
DROP TRIGGER IF EXISTS url_mem_insert;
CREATE TRIGGER url_mem_insert
BEFORE INSERT ON urls
FOR EACH ROW BEGIN
SET NEW.id= memc_increment('urls:sequence');
SET @mm= memc_set(concat('urls:',NEW.id), NEW.url);
END
DELIMITER ;
insert into urls (url) values ('http://google.com');
insert into urls (url) values ('http://www.ooso.net/index.php');
insert into urls (url) values ('http://www.ooso.net/');
insert into urls (url) values ('http://slashdot.org');
insert into urls (url) values ('http://mysql.com');
select * from urls;
select memc_get('urls:1');
select memc_get('urls:2');
select memc_get('urls:3');
select memc_get('urls:4');
select memc_get('urls:5');