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目录
- 应用环境
- 数据库同步方式
- 创建数据库表
- 配置数据库my.ini文件
- my.ini文件简单释义
- 配置双向同步
- 配置项释义
- 设置主机并启动从服务器线程
- 测试同步
- 解决自增长列的问题
- 模拟测试自增长列解决方案
- 故障排除
- MySQL版本间复制兼容性问题
- ERROR 1201 (HY000)
数据库服务器
虚拟机
OS: Windows Server 2003
1.数据库服务器242
IP:192.168.206.242
2.数据库服务器243
IP:192.168.206.243
MySQL版本
版本号：5.5.2
查询语句：SELECT VERSION();
两台服务器互为主从，双向同步数据
为试验双向同步，简单编写了一个创建数据库和一个用户表的语句。
并分别在服务器242和243上的MySQL中执行语句。
01 |
CREATE DATABASE wilsondb; |
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DROP TABLE IF EXISTS `userinfo`; |
07 |
CREATE TABLE `userinfo` ( |
09 |
`UserId` int(11) NOT NULL AUTO_INCREMENT, |
11 |
`UserName` varchar(64) DEFAULT NULL, |
13 |
PRIMARY KEY (`UserId`) |
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) ENGINE=InnoDB DEFAULT CHARSET=utf8; |
在242和243服务器MySQL的安装目录下找到my.ini文件
1.my.ini文件各配置项简单释义
my.ini详情及简单释义
001 |
# MySQL Server Instance Configuration File |
002 |
# ---------------------------------------------------------------------- |
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# Generated by the MySQL Server Instance Configuration Wizard |
006 |
# Installation Instructions |
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# ---------------------------------------------------------------------- |
009 |
# On Linux you can copy this file to /etc/my.cnf to set global options, |
010 |
# mysql-data-dir/my.cnf to set server-specific options |
011 |
# (@localstatedir@ for this installation) or to |
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# ~/.my.cnf to set user-specific options. |
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# On Windows you should keep this file in the installation directory |
015 |
# of your server (e.g. C:\Program Files\MySQL\MySQL Server X.Y). To |
016 |
# make sure the server reads the config file use the startup option |
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# To run run the server from the command line, execute this in a |
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# command line shell, e.g. |
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# mysqld --defaults-file="C:\Program Files\MySQL\MySQL Server X.Y\my.ini" |
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# To install the server as a Windows service manually, execute this in a |
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# command line shell, e.g. |
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# mysqld --install MySQLXY --defaults-file="C:\Program Files\MySQL\MySQL Server X.Y\my.ini" |
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# And then execute this in a command line shell to start the server, e.g. |
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# Guildlines for editing this file |
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# ---------------------------------------------------------------------- |
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# In this file, you can use all long options that the program supports. |
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# If you want to know the options a program supports, start the program |
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# with the "--help" option. |
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# More detailed information about the individual options can also be |
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# found in the manual. |
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# ---------------------------------------------------------------------- |
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# The following options will be read by MySQL client applications. |
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# Note that only client applications shipped by MySQL are guaranteed |
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# to read this section. If you want your own MySQL client program to |
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# honor these values, you need to specify it as an option during the |
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# MySQL client library initialization. |
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default-character-set=utf8 |
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# ---------------------------------------------------------------------- |
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# The following options will be read by the MySQL Server. Make sure that |
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# you have installed the server correctly (see above) so it reads this |
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# The TCP/IP Port the MySQL Server will listen on |
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#Path to installation directory. All paths are usually resolved relative to this. |
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basedir="C:/Program Files/MySQL/MySQL Server 5.5/" |
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#Path to the database root |
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datadir="C:/Documents and Settings/All Users/Application Data/MySQL/MySQL Server 5.5/Data/" |
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# The default character set that will be used when a new schema or table is |
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# created and no character set is defined |
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character-set-server=utf8 |
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# The default storage engine that will be used when create new tables when |
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default-storage-engine=INNODB |
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# Set the SQL mode to strict |
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# 参数详细：http://www.cnblogs.com/ainiaa/archive/2010/12/31/1923002.html |
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sql-mode="STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION" |
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# The maximum amount of concurrent sessions the MySQL server will |
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# allow. One of these connections will be reserved for a user with |
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# SUPER privileges to allow the administrator to login even if the |
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# connection limit has been reached. |
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# 服务器端最大并发数，一个是留给超级管理员权限登录数据库 |
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# Query cache is used to cache SELECT results and later return them |
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# without actual executing the same query once again. Having the query |
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# cache enabled may result in significant speed improvements, if your |
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# have a lot of identical queries and rarely changing tables. See the |
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# "Qcache_lowmem_prunes" status variable to check if the current value |
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# is high enough for your load. |
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# Note: In case your tables change very often or if your queries are |
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# textually different every time, the query cache may result in a |
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# slowdown instead of a performance improvement. |
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# 查询缓存的大小，Note：在查询常变，表结构常变的情况下，用缓存反而不好 |
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# The number of open tables for all threads. Increasing this value |
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# increases the number of file descriptors that mysqld requires. |
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# Therefore you have to make sure to set the amount of open files |
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# allowed to at least 4096 in the variable "open-files-limit" in |
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# section [mysqld_safe] |
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# Maximum size for internal (in-memory) temporary tables. If a table |
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# grows larger than this value, it is automatically converted to disk |
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# based table This limitation is for a single table. There can be many |
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# How many threads we should keep in a cache for reuse. When a client |
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# disconnects, the client's threads are put in the cache if there aren't |
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# more than thread_cache_size threads from before. This greatly reduces |
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# the amount of thread creations needed if you have a lot of new |
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# connections. (Normally this doesn't give a notable performance |
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# improvement if you have a good thread implementation.) |
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#*** MyISAM Specific options |
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# The maximum size of the temporary file MySQL is allowed to use while |
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# recreating the index (during REPAIR, ALTER TABLE or LOAD DATA INFILE. |
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# If the file-size would be bigger than this, the index will be created |
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# through the key cache (which is slower). |
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myisam_max_sort_file_size=100G |
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# If the temporary file used for fast index creation would be bigger |
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# than using the key cache by the amount specified here, then prefer the |
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# key cache method. This is mainly used to force long character keys in |
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# large tables to use the slower key cache method to create the index. |
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myisam_sort_buffer_size=52M |
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# Size of the Key Buffer, used to cache index blocks for MyISAM tables. |
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# Do not set it larger than 30% of your available memory, as some memory |
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# is also required by the OS to cache rows. Even if you're not using |
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# MyISAM tables, you should still set it to 8-64M as it will also be |
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# used for internal temporary disk tables. |
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# MyISAM表索引缓存大小，建议不要超过可用内存的30% |
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# Size of the buffer used for doing full table scans of MyISAM tables. |
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# Allocated per thread, if a full scan is needed. |
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# MyISAM表全表扫描时的缓冲区大小（顺序读取） |
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read_rnd_buffer_size=256K |
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# This buffer is allocated when MySQL needs to rebuild the index in |
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# REPAIR, OPTIMZE, ALTER table statements as well as in LOAD DATA INFILE |
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# into an empty table. It is allocated per thread so be careful with |
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sort_buffer_size=256K |
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#*** INNODB Specific options *** |
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# Use this option if you have a MySQL server with InnoDB support enabled |
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# but you do not plan to use it. This will save memory and disk space |
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# and speed up some things. |
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# Additional memory pool that is used by InnoDB to store metadata |
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# information. If InnoDB requires more memory for this purpose it will |
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# start to allocate it from the OS. As this is fast enough on most |
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# recent operating systems, you normally do not need to change this |
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# value. SHOW INNODB STATUS will display the current amount used. |
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# 设置InnoDB存储引擎存放数据字典信息和内部数据结构的内存大小 |
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innodb_additional_mem_pool_size=4M |
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# If set to 1, InnoDB will flush (fsync) the transaction logs to the |
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# disk at each commit, which offers full ACID behavior. If you are |
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# willing to compromise this safety, and you are running small |
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# transactions, you may set this to 0 or 2 to reduce disk I/O to the |
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# logs. Value 0 means that the log is only written to the log file and |
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# the log file flushed to disk approximately once per second. Value 2 |
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# means the log is written to the log file at each commit, but the log |
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# file is only flushed to disk approximately once per second. |
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# N（N是后面设置的值）次事务提交或事务外的指令就需要把日志写入硬盘 |
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innodb_flush_log_at_trx_commit=1 |
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# The size of the buffer InnoDB uses for buffering log data. As soon as |
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# it is full, InnoDB will have to flush it to disk. As it is flushed |
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# once per second anyway, it does not make sense to have it very large |
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# (even with long transactions). |
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# 设置InnoDB存储引擎的事务日志使用的缓冲区 |
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innodb_log_buffer_size=1520K |
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# InnoDB, unlike MyISAM, uses a buffer pool to cache both indexes and |
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# row data. The bigger you set this the less disk I/O is needed to |
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# access data in tables. On a dedicated database server you may set this |
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# parameter up to 80% of the machine physical memory size. Do not set it |
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# too large, though, because competition of the physical memory may |
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# cause paging in the operating system. Note that on 32bit systems you |
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# might be limited to 2-3.5G of user level memory per process, so do not |
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# 设置InnoDB存放索引和表数据的最大缓冲区大小 |
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innodb_buffer_pool_size=147M |
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# Size of each log file in a log group. You should set the combined size |
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# of log files to about 25%-100% of your buffer pool size to avoid |
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# unneeded buffer pool flush activity on log file overwrite. However, |
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# note that a larger logfile size will increase the time needed for the |
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innodb_log_file_size=74M |
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# Number of threads allowed inside the InnoDB kernel. The optimal value |
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# depends highly on the application, hardware as well as the OS |
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# scheduler properties. A too high value may lead to thread thrashing. |
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innodb_thread_concurrency=8 |
PS: 上面的折叠代码试验在chrome浏览器下需要手动刷一下页面才能展开
2.配置双向同步
242服务器上配置：
在[mysqld]这个Section中加入如下key/value对：
#---------------------------------------------
server-id=242
log-bin=mysql-bin
relay-log=relay-bin
relay-log-index=relay-bin-index
replicate-do-db=wilsondb
#---------------------------------------------
243服务器上配置：
在[mysqld]这个Section中加入如下key/value对：
#---------------------------------------------
server-id=243
log-bin=mysql-bin
relay-log=relay-bin
relay-log-index=relay-bin-index
replicate-do-db=wilsondb
#---------------------------------------------
3.配置项释义【复制启动选项】
① server-id：标识，唯一，值范围在：1至2^23-1
② log-bin：配置是否在数据库有变动时写二进制日志
查看日志是否开启：
show variables like '%bin';
③ relay-log：这个不太会解释，Master二进制日志到Slave的IO进程会写到relay-log最后一行，Slave的sql进程时刻监测着relay-log是否有变化，有变化则解析执行.
④ replicate-to-db:同步的数据库
⑤ 其它复制启动选项： http://dev./doc/refman/5.1/zh/replication.html#replication-options
在服务器242和243上配置好之后，分别重启MySQL服务，如果重启失败则说明配置有误!
服务242上用MySQL命令行工具执行如下语句：
mysql> stop slave;
mysql> change master to master_host='192.168.206.243',master_user='root',master_password='abcd';
mysql> start slave;
mysql> show slave status\G;
#master_host的最大长度为60
#master_user的最大长度为16
#master_password最大长度为32
服务243上上用MySQL命令行工具执行如下语句：
mysql> stop slave;
mysql> change master tomaster_host='192.168.206.242',master_user='root',master_password='abcd';
mysql> start slave;
mysql> show slave status\G;
Show Slave Status 部分释义
① Slave_IO_Status:线程已经连接上主服务器，正等待二进制日志事件到达。如果主服务器正空闲，会持续较长的时间。如果等待持续slave_read_timeout秒，则发生超时。此时，线程认为连接被中断并企图重新连接。
更多Slave_IO_Status: http://dev./doc/refman/5.1/zh/replication.html#slave-io-thread-states
② Master_Host: 主机IP
③ Master_Log_File和Master_LOG_POS选项执行CHANGE MASTER TO来告诉从服务器重新从该点读取二进制日志
④ Slave_IO_Running:是否要从Master复制二进制数据
⑤ Slave_SQL_Running:是否执行从Master复制过来的二进制数据
⑥ Slave_IO_Running和Slave_SQL_Running的值均为Yes时为同步开启;
⑦ Last_Errno和Last_Error是错误信息的提示（如果有错误）
⑧ Seconds_Behind_Master：Slave的数据落后Master的多少秒，同步完成为0
为了方便测试，装了一个Navicat for MySQL;
对242和243数据库进行了双向的增、删、改操作;
结果：最后都能正确的双向同步。
原因：当同步断开，两台服务器分别有新数据进入，那么主键ID是自增长列会出现冲突的情况，会导致同步无法继续。
在242和243服务器MySQL的安装目录下找到my.ini文件
分别在文件最后添入下面配置项：
服务器242：
#-------------------------------------
auto_increment_offset=1
auto_increment_increment=2
#-------------------------------------
服务器243：
#-------------------------------------
auto_increment_offset=2
auto_increment_increment=2
#-------------------------------------
查看修改后的属性值：
SHOW VARIABLES LIKE 'auto_inc%';
服务器242：
服务器243：
通过调整auto_increment_offset和auto_increment_increment让两台服务器自增长值不重复，这样多台服务器自增的问题就解决了;
（此项操作为了看自增更明显，我重新生成了表，然后再做了配置，其实本不需要重新生成表结构!）
测试过程模拟同步在断开后，两个数据库分别都有数据插入，然后再开启同步，是否会有自增ID的冲突。
1.先分别在服务器242和243上停止Slave线程
2.然后分别向服务器242和243所在数据库中分别插入数据
很明显，分别插入时，自增列也不会重复;
3.分别开启服务器242和243的Slave线程
4.查看同步后的数据
-------------------------------------------------------------
大功告成，同步成功，且没有发生冲突！
试验过程中遇到几个主要问题：
1.MySQL版本间复制兼容性
官方是推荐使用最近的版本，复制功能在不断改进中，同时推荐主从服务器使用相同的版本;
为了避免出现一些兼容性的问题，这里两台数据库服务器上的MySQL安装了相同的版本;
不同MySQL版本之间的复制兼容性: http://dev./doc/refman/5.1/zh/replication.html#replication-compatibility
2.ERROR 1201 (HY000): Could not initialize master info structure; more error messages can be found in the MySQL error log
在start slave;时出现error 1201(HY000)，出错后注意用show slave status\G 看错误提示（Last_IO_Error和Last_SQL_Error）。后台根据提示定位是在没关掉同步的情况下进行了一些冲突的SQL操作，
解决步骤： ① 停止SQL服务
② 删除master.info和relay-log.info文件
③ change master to master_host='XXXXXX',
master_user='XXXX',master_password='XXXX';
④ 重启SQL服务器，再start slave;
过程中远不止遇到这几个错误，没记录下细节，都是看相关提示修正的，都是些操作问题或者是细心问题;
作 者： Porschev[钟慰]
出 处： http://www.cnblogs.com/zhongweiv/
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