| 目錄 |
| 應用環境 |
數據庫服務器
虛擬機
OS: Windows Server 2003
1.數據庫服務器242
IP:192.168.206.242
2.數據庫服務器243
IP:192.168.206.243
MySQL版本
版本號：5.5.2
查詢語句：SELECT VERSION();
| 數據庫同步方式 |
兩台服務器互為主從，雙向同步數據
| 創建數據庫表 |
為試驗雙向同步，簡單編寫了一個創建數據庫和一個用戶表的語句。
並分別在服務器242和243上的MySQL中執行語句。
CREATE DATABASE wilsondb; USE wilsondb; DROP TABLE IF EXISTS `userinfo`; CREATE TABLE `userinfo` ( `UserId` int(11) NOT NULL AUTO_INCREMENT, `UserName` varchar(64) DEFAULT NULL, PRIMARY KEY (`UserId`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
| 配置數據庫my.ini文件 |
在242和243服務器MySQL的安裝目錄下找到my.ini文件
my.ini詳情及簡單釋義
# MySQL Server Instance Configuration File # ---------------------------------------------------------------------- # Generated by the MySQL Server Instance Configuration Wizard # # # Installation Instructions # ---------------------------------------------------------------------- # # On Linux you can copy this file to /etc/my.cnf to set global options, # mysql-data-dir/my.cnf to set server-specific options # (@localstatedir@ for this installation) or to # ~/.my.cnf to set user-specific options. # # On Windows you should keep this file in the installation directory # of your server (e.g. C:\Program Files\MySQL\MySQL Server X.Y). To # make sure the server reads the config file use the startup option # "--defaults-file". # # To run run the server from the command line, execute this in a # command line shell, e.g. # mysqld --defaults-file="C:\Program Files\MySQL\MySQL Server X.Y\my.ini" # # To install the server as a Windows service manually, execute this in a # command line shell, e.g. # mysqld --install MySQLXY --defaults-file="C:\Program Files\MySQL\MySQL Server X.Y\my.ini" # # And then execute this in a command line shell to start the server, e.g. # net start MySQLXY # # # Guildlines for editing this file # ---------------------------------------------------------------------- # # In this file, you can use all long options that the program supports. # If you want to know the options a program supports, start the program # with the "--help" option. # # More detailed information about the individual options can also be # found in the manual. # # # CLIENT SECTION # ---------------------------------------------------------------------- # # The following options will be read by MySQL client applications. # Note that only client applications shipped by MySQL are guaranteed # to read this section. If you want your own MySQL client program to # honor these values, you need to specify it as an option during the # MySQL client library initialization. # # 客戶端 [client] # 端口號 port=3306 [mysql] # 字符集 default-character-set=utf8 # SERVER SECTION # ---------------------------------------------------------------------- # # The following options will be read by the MySQL Server. Make sure that # you have installed the server correctly (see above) so it reads this # file. # [mysqld] # The TCP/IP Port the MySQL Server will listen on # MySQL端口號 port=3306 #Path to installation directory. All paths are usually resolved relative to this. # 安裝路徑 basedir="C:/Program Files/MySQL/MySQL Server 5.5/" #Path to the database root # 數據庫根路徑 datadir="C:/Documents and Settings/All Users/Application Data/MySQL/MySQL Server 5.5/Data/" # The default character set that will be used when a new schema or table is # created and no character set is defined # 字符集 character-set-server=utf8 # The default storage engine that will be used when create new tables when # 默認存儲引擎 default-storage-engine=INNODB # Set the SQL mode to strict # 設置嚴格SQL模型 # 參數詳細：http://www.cnblogs.com/ainiaa/archive/2010/12/31/1923002.html sql-mode="STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION" # The maximum amount of concurrent sessions the MySQL server will # allow. One of these connections will be reserved for a user with # SUPER privileges to allow the administrator to login even if the # connection limit has been reached. # 服務器端最大並發數，一個是留給超級管理員權限登錄數據庫 max_connections=100 # Query cache is used to cache SELECT results and later return them # without actual executing the same query once again. Having the query # cache enabled may result in significant speed improvements, if your # have a lot of identical queries and rarely changing tables. See the # "Qcache_lowmem_prunes" status variable to check if the current value # is high enough for your load. # Note: In case your tables change very often or if your queries are # textually different every time, the query cache may result in a # slowdown instead of a performance improvement. # 查詢緩存的大小，Note：在查詢常變，表結構常變的情況下，用緩存反而不好 query_cache_size=0 # The number of open tables for all threads. Increasing this value # increases the number of file descriptors that mysqld requires. # Therefore you have to make sure to set the amount of open files # allowed to at least 4096 in the variable "open-files-limit" in # section [mysqld_safe] # Table高速緩存的數量 table_cache=256 # Maximum size for internal (in-memory) temporary tables. If a table # grows larger than this value, it is automatically converted to disk # based table This limitation is for a single table. There can be many # of them. # 單張臨時表的大小限制 tmp_table_size=26M # How many threads we should keep in a cache for reuse. When a client # disconnects, the client's threads are put in the cache if there aren't # more than thread_cache_size threads from before. This greatly reduces # the amount of thread creations needed if you have a lot of new # connections. (Normally this doesn't give a notable performance # improvement if you have a good thread implementation.) # 緩存多少線程給客戶端使用 thread_cache_size=8 #*** MyISAM Specific options # The maximum size of the temporary file MySQL is allowed to use while # recreating the index (during REPAIR, ALTER TABLE or LOAD DATA INFILE. # If the file-size would be bigger than this, the index will be created # through the key cache (which is slower). # 重建索引時臨時文件允許的最大值 myisam_max_sort_file_size=100G # If the temporary file used for fast index creation would be bigger # than using the key cache by the amount specified here, then prefer the # key cache method. This is mainly used to force long character keys in # large tables to use the slower key cache method to create the index. # 表發生變化重新排序需要的緩沖大小 myisam_sort_buffer_size=52M # Size of the Key Buffer, used to cache index blocks for MyISAM tables. # Do not set it larger than 30% of your available memory, as some memory # is also required by the OS to cache rows. Even if you're not using # MyISAM tables, you should still set it to 8-64M as it will also be # used for internal temporary disk tables. # MyISAM表索引緩存大小，建議不要超過可用內存的30% key_buffer_size=8M # Size of the buffer used for doing full table scans of MyISAM tables. # Allocated per thread, if a full scan is needed. # MyISAM表全表掃描時的緩沖區大小（順序讀取） read_buffer_size=64K # 隨機讀取的緩沖區大小 read_rnd_buffer_size=256K # This buffer is allocated when MySQL needs to rebuild the index in # REPAIR, OPTIMZE, ALTER table statements as well as in LOAD DATA INFILE # into an empty table. It is allocated per thread so be careful with # large settings. # 排序使用的緩沖區大小 sort_buffer_size=256K #*** INNODB Specific options *** # Use this option if you have a MySQL server with InnoDB support enabled # but you do not plan to use it. This will save memory and disk space # and speed up some things. #skip-innodb # Additional memory pool that is used by InnoDB to store metadata # information. If InnoDB requires more memory for this purpose it will # start to allocate it from the OS. As this is fast enough on most # recent operating systems, you normally do not need to change this # value. SHOW INNODB STATUS will display the current amount used. # 設置InnoDB存儲引擎存放數據字典信息和內部數據結構的內存大小 innodb_additional_mem_pool_size=4M # If set to 1, InnoDB will flush (fsync) the transaction logs to the # disk at each commit, which offers full ACID behavior. If you are # willing to compromise this safety, and you are running small # transactions, you may set this to 0 or 2 to reduce disk I/O to the # logs. Value 0 means that the log is only written to the log file and # the log file flushed to disk approximately once per second. Value 2 # means the log is written to the log file at each commit, but the log # file is only flushed to disk approximately once per second. # N（N是后面設置的值）次事務提交或事務外的指令就需要把日志寫入硬盤 innodb_flush_log_at_trx_commit=1 # The size of the buffer InnoDB uses for buffering log data. As soon as # it is full, InnoDB will have to flush it to disk. As it is flushed # once per second anyway, it does not make sense to have it very large # (even with long transactions). # 設置InnoDB存儲引擎的事務日志使用的緩沖區 innodb_log_buffer_size=1520K # InnoDB, unlike MyISAM, uses a buffer pool to cache both indexes and # row data. The bigger you set this the less disk I/O is needed to # access data in tables. On a dedicated database server you may set this # parameter up to 80% of the machine physical memory size. Do not set it # too large, though, because competition of the physical memory may # cause paging in the operating system. Note that on 32bit systems you # might be limited to 2-3.5G of user level memory per process, so do not # set it too high. # 設置InnoDB存放索引和表數據的最大緩沖區大小 innodb_buffer_pool_size=147M # Size of each log file in a log group. You should set the combined size # of log files to about 25%-100% of your buffer pool size to avoid # unneeded buffer pool flush activity on log file overwrite. However, # note that a larger logfile size will increase the time needed for the # recovery process. # 一個InnoDB事條日志的大小 innodb_log_file_size=74M # Number of threads allowed inside the InnoDB kernel. The optimal value # depends highly on the application, hardware as well as the OS # scheduler properties. A too high value may lead to thread thrashing. # InnoDB最大並發線程數 innodb_thread_concurrency=8PS: 上面的折疊代碼試驗在chrome瀏覽器下需要手動刷一下頁面才能展開
242服務器上配置：
在[mysqld]這個Section中加入如下key/value對：
#---------------------------------------------
server-id=242
log-bin=mysql-bin
relay-log=relay-bin
relay-log-index=relay-bin-index
replicate-do-db=wilsondb
#---------------------------------------------
243服務器上配置：
在[mysqld]這個Section中加入如下key/value對：
#---------------------------------------------
server-id=243
log-bin=mysql-bin
relay-log=relay-bin
relay-log-index=relay-bin-index
replicate-do-db=wilsondb
#---------------------------------------------
① server-id：標識，唯一，值范圍在：1至2^23-1
② log-bin：配置是否在數據庫有變動時寫二進制日志
查看日志是否開啟：
show variables like '%bin';
③ relay-log：這個不太會解釋，Master二進制日志到Slave的IO進程會寫到relay-log最后一行，Slave的sql進程時刻監測着relay-log是否有變化，有變化則解析執行.
④ replicate-to-db:同步的數據庫
⑤ 其它復制啟動選項： http://dev.mysql.com/doc/refman/5.1/zh/replication.html#replication-options
在服務器242和243上配置好之后，分別重啟MySQL服務，如果重啟失敗則說明配置有誤!
| 設置主機並啟動從服務器線程 |
服務242上用MySQL命令行工具執行如下語句：
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的最大長度為60
#master_user的最大長度為16
#master_password最大長度為32
服務243上上用MySQL命令行工具執行如下語句：
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;
① Slave_IO_Status:線程已經連接上主服務器，正等待二進制日志事件到達。如果主服務器正空閑，會持續較長的時間。如果等待持續slave_read_timeout秒，則發生超時。此時，線程認為連接被中斷並企圖重新連接。
更多Slave_IO_Status: http://dev.mysql.com/doc/refman/5.1/zh/replication.html#slave-io-thread-states
② Master_Host: 主機IP
③ Master_Log_File和Master_LOG_POS選項執行CHANGE MASTER TO來告訴從服務器重新從該點讀取二進制日志
④ Slave_IO_Running:是否要從Master復制二進制數據
⑤ Slave_SQL_Running:是否執行從Master復制過來的二進制數據
⑥ Slave_IO_Running和Slave_SQL_Running的值均為Yes時為同步開啟;
⑦ Last_Errno和Last_Error是錯誤信息的提示（如果有錯誤）
⑧ Seconds_Behind_Master：Slave的數據落后Master的多少秒，同步完成為0
| 測試同步 |
為了方便測試，裝了一個Navicat for MySQL;
對242和243數據庫進行了雙向的增、刪、改操作;
結果：最后都能正確的雙向同步。
| 解決自增長列的問題 |
原因：當同步斷開，兩台服務器分別有新數據進入，那么主鍵ID是自增長列會出現沖突的情況，會導致同步無法繼續。
在242和243服務器MySQL的安裝目錄下找到my.ini文件
分別在文件最后添入下面配置項：
服務器242：
#-------------------------------------
auto_increment_offset=1
auto_increment_increment=2
#-------------------------------------
服務器243：
#-------------------------------------
auto_increment_offset=2
auto_increment_increment=2
#-------------------------------------
查看修改后的屬性值：
SHOW VARIABLES LIKE 'auto_inc%';
服務器242：
服務器243：
通過調整auto_increment_offset和auto_increment_increment讓兩台服務器自增長值不重復，這樣多台服務器自增的問題就解決了;
（此項操作為了看自增更明顯，我重新生成了表，然后再做了配置，其實本不需要重新生成表結構!）
| 模擬測試自增長列解決方案 |
測試過程模擬同步在斷開后，兩個數據庫分別都有數據插入，然后再開啟同步，是否會有自增ID的沖突。
1.先分別在服務器242和243上停止Slave線程
2.然后分別向服務器242和243所在數據庫中分別插入數據
很明顯，分別插入時，自增列也不會重復;
3.分別開啟服務器242和243的Slave線程
4.查看同步后的數據
-------------------------------------------------------------
大功告成，同步成功，且沒有發生沖突！
| 故障排除 |
試驗過程中遇到幾個主要問題：
官方是推薦使用最近的版本，復制功能在不斷改進中，同時推薦主從服務器使用相同的版本;
為了避免出現一些兼容性的問題，這里兩台數據庫服務器上的MySQL安裝了相同的版本;
不同MySQL版本之間的復制兼容性: http://dev.mysql.com/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;時出現error 1201(HY000)，出錯后注意用show slave status\G 看錯誤提示（Last_IO_Error和Last_SQL_Error）。后台根據提示定位是在沒關掉同步的情況下進行了一些沖突的SQL操作，
解決步驟： ① 停止SQL服務
② 刪除master.info和relay-log.info文件
③ change master to master_host='XXXXXX',
master_user='XXXX',master_password='XXXX';
④ 重啟SQL服務器，再start slave;
過程中遠不止遇到這幾個錯誤，沒記錄下細節，都是看相關提示修正的，都是些操作問題或者是細心問題;