利用mysql函数更新memcached
Memcached Functions for MYSQL官方主页：
https://launchpad.net/memcached-udfs
两篇基本文章：
http://www.libing.name/2009/02/06/mysql-map-data-to-memcached.html
http://www.libing.name/2008/02/26/mysql-map-memcached.html
安装和验证的SQL语句：
http://hg.tangent.org/memcached_functions_mysql/file/724eeccc55bc/README
安装：
1.安装mysql
2.安装memcached
3.启动mysql,memcached
/usr/local/bin/memcached -p 22222 -m 64m -u root -d
4.安装Memcached Functions for MYSQL
tar xzvf memcached_functions_mysql-0.2.tar.gz
cd memcached_functions_mysql-0.2
./configure –with-mysql=MYSQL_DIR/bin/mysql_config –libdir=MYSQL_DIR/lib/mysql/
make
make install
5.将UDFs加载到MySQL中（UDF=User Defined Function）
memc_servers_set()
mysql> create function memc_servers_set returns int soname "libmemcached_functions_mysql.so";
memc_set()
mysql> create function memc_set returns int soname "libmemcached_functions_mysql.so";
memc_get()
mysql> create function memc_get returns string soname "libmemcached_functions_mysql.so";
memc_delete()
mysql> create function memc_delete returns string soname "libmemcached_functions_mysql.so";
......
其他函数的加载省略
6.验证
select memc_servers_set('127.0.0.1:22222');
select memc_set('key','value');
select memc_get('key');
select memc_delete('key');
7.触发器更新memcached
（1）创建表
create table memc_test(
key varchar(100),
value varchar(100)
);
（2）创建触发器
delimiter ;;
create trigger memc_add after insert on memc_test for each row begin
set @tmp=memc_servers_set('localhost:11211');
set @tmp=memc_set(NEW.key,NEW.value);
end;;
delimiter ;
delimiter ;;
create trigger memc_update after update on memc_test for each row begin
set @tmp=memc_servers_set('localhost:11211');
set @tmp=memc_set(NEW.key,NEW.value);
end;;
delimiter ;
delimiter ;;
create trigger memc_del after delete on memc_test for each row begin
set @tmp=memc_servers_set('localhost:11211');
set @tmp=memc_delete(OLD.key);
end;;
delimiter ;
（3）测试
查询memcached
telnet localhost 22222
get key1
END
没有值
向数据库中插入一条
insert into memc_test values('key1','value1');
get key1
value1
END
得到值，证明UDFs正常工作了。