MySQL Memcached UDF安装注意事项

近期测试MySQL Memcached UDF在几个环境下分别进行了安装，安装中碰到了很多的问题，总结一下。安装的过程真是折腾死了由于安装由几部分组成，各个部分的版本都有冲突，而且还有不向下兼容的情况，所以频频安装出错。

 

1 介绍

mysql memcached UDF 其实就是通过libmemcached来使用memcache的一系列函数，通过这些函数，你能 对memcache进行get, set, cas, append, prepend, delete, increment, decrement objects操作，如果我们通过mysql trigger来使用这些函数，那么就能通过mysql更好的，更自动的管理memcache!

mysql：http://downloads.mysql.com/archives/
libevent下载：wget http://www.monkey.org/~provos/libevent-1.2.tar.gz
libmemcached下载：http://download.tangent.org/
memcached下载：http://pecl.php.net/package/memcached
memcached_functions_mysql下载：http://download.tangent.org/

2 安装

1）安装libevent+memcache

什么是 memcached ？顾名思义，就是内存缓存。按照其官网的介绍：memcached 是高性能、分布式的内存对象缓存系统，意图用来通过减轻数据库的负载来提高动态 WEB 应用的速度。读写内存的速度显然要比读写文件系统或数据库系统要快得多，将动态数据缓存在内存中，显然要比其他缓存，有效得多。添加内存能带来的性能提升，对于服务器来说，要比其他方式有效得多。对于大中型网站，部署应用 memcached 将收到很好的效果。

Debian 系直接 $ sudo apt-get install memcached 都搞定，不然还需要分别安装libevent与memcached

只是编译安装时注意64位的要增加64位选项 $ ./configure --enable-64bit 将编译 64 位的版本。

2）安装libmemcached
 

$ wget http://download.tangent.org/libmemcached-0.34.tar.gz

$ tar xvzf libmemcached-0.34.tar.gz 

$ cd libmemcached-0.34
$  ./configure --prefix=/usr/local/libmemcached34 --with-memcached=/usr/bin/memcached
$ sudo make

$ sudo make install

$ sudo chmod 777 /etc/ld.so.conf

$ echo "/usr/local/libmemcached34" >> /etc/ld.so.conf

$ ldconfig

不要用libmemcached-0.42.tar.gz，会遇到servers.c:263:28: error: ‘memcached_st’ has no member named ‘hosts’servers.c:264:28: error: ‘memcached_st’ has no member named ‘hosts’但是libmemcached-0.34到0.37都没有这个问题

这里要使用0.34 不然会遇到 ERROR 1126 (HY000) at line 38: Can't open shared library 'libmemcached_functions_mysql.so' (errno: 0 /usr/local/mysql/lib/plugin/libmemcached_functions_mysql.so: undefined symbol: memcached_string_append) 

 

3）安装memcached_functions_mysql 

$ wget http://download.tangent.org/memcached_functions_mysql-0.9.tar.gz

$ tar zxvf memcached_functions_mysql-0.9.tar.gz
$ cd memcached_functions_mysql-0.9
$ ./configure --prefix=/usr/local/memcache_mysql --with-mysql=/usr/local/mysql/bin/mysql_config --with-libmemcached=/usr/local/libmemcached34

如果缺少pkg-config安装一下

$ sudo apt-get install pkg-config

$ sudo make

$ sudo make install

4）拷贝lib文件到mysql的plugin下面

$ sudo cp /usr/local/memcache_mysql/lib/libmemcached_functions*   /usr/local/mysql/lib/mysql/plugin 

5）添加memcache UDF 函数

mysql> source sql/install_functions.sql

这样我们就可以使用mysql memcached UDF 了，我们可以通过下面语句查看是否已经正常安装

mysql> select * from mysql.func;
+------------------------------+-----+---------------------------------+----------+
| name | ret | dl | type |
+------------------------------+-----+---------------------------------+----------+
| memc_add | 2 | libmemcached_functions_mysql.so | function |
| memc_add_by_key | 2 | libmemcached_functions_mysql.so | function |
| memc_servers_set | 2 | libmemcached_functions_mysql.so | function |
32 rows in set (0.00 sec)

添加trigger，就是向memcache内insert，update，deletel等，参照：
1）memcached_functions_mysql-0.9/sql 目录下的trigger_fun.sql
2）或者文档：http://dev.mysql.com/doc/refman/5.1/en/ha-memcached-interfaces-mysqludf.html

如果懒得看就看我后边的例子

3 测试

mysql> select memc_servers_set('127.0.0.1:11211')

注意：如果mysql restart，需要重新运行这句以建立与memcached之间的关系

 

mysql> select memc_servers_behavior_set('MEMCACHED_BEHAVIOR_NO_BLOCK','1');
+--------------------------------------------------------------+
| memc_servers_behavior_set('MEMCACHED_BEHAVIOR_NO_BLOCK','1') |
+--------------------------------------------------------------+
| 0 |
+--------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> select memc_servers_behavior_set('MEMCACHED_BEHAVIOR_TCP_NODELAY','1');
+-----------------------------------------------------------------+
| memc_servers_behavior_set('MEMCACHED_BEHAVIOR_TCP_NODELAY','1') |
+-----------------------------------------------------------------+
| 0 |
+-----------------------------------------------------------------+
1 row in set (0.00 sec)

注意：设置MEMCACHED_BEHAVIOR_NO_BLOCK为打开状态，这样在memcached出现问题时（不能连接时）
数据继续插入到mysql中，报错提示，如果不设置此值，如果memcached失败，mysql需要等到timeout
才可以插入到表中。

 

mysql> use test;

Database changed

 

mysql> create table xxd (id int, value varchar(100));    

 

mysql> create trigger xxdmmci after insert on xxd for each row set @tmp = memc_set(NEW.id, NEW.value);

 

mysql> create trigger xxdmmcu after update on xxd for each row set @tmp = memc_set(NEW.id, NEW.value);

 

mysql> create trigger xxdmmcd before delete on xxd for each row set @tmp = memc_delete(OLD.id);

 

mysql> insert into xxd values(1, 'xxd'),(2,'xxd79'),(3, 'buro79xxd');         

Query OK, 3 rows affected (0.00 sec)

Records: 3  Duplicates: 0  Warnings: 0

 

mysql> select memc_get('2');
+----------------------------+
| memc_get('2')              |
+----------------------------+
| xxd79 |
+----------------------------+
1 row in set (0.00 sec)

 

mysql> update xxd set value='xxd_new' where id=1;

Query OK, 1 row affected (0.00 sec)

Rows matched: 1  Changed: 1  Warnings: 0

 

mysql> select memc_get('1');
+----------------------------+
| memc_get('1')              |
+----------------------------+
| xxd_new |

+----------------------------+
1 row in set (0.00 sec)

 

mysql> delete from xxd where id=1;

Query OK, 1 row affected (0.00 sec)

 

mysql> select memc_get('1');
+----------------------------+
| memc_get('1')              |
+----------------------------+
| NULL |
+----------------------------+
1 row in set (0.00 sec)

 

mysql> exit

 

$ telnet 127.0.0.1 11211

Trying 127.0.0.1...

Connected to 127.0.0.1.

Escape character is '^]'.

get 1

END

get 2

VALUE 2 0 5

xxd79

END

get 3

VALUE 3 0 9

buro79xxd

END

quit

Connection closed by foreign host.

 

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