之前公司大部分项目都上了5.5版本，手上刚好有个项目(*交易平台)数据量不是很大，单台服务器在线上跑得比较稳定，很少去搭理，为了统一版本于是打算升级到MySQL5.5版本...在贺总的协助下完成了升级工作..下面是具体的升级过程及二个大版本之间一些要注意的参数！
#注释掉default_table_type = MyISAM 在5.5里已经不识别了#注释掉myisam_max_extra_sort_file_size 在5.5里已经不识别了
#innodb_file_io_threads已经不识别了，改成innodb_read_io_threads = 8innodb_write_io_threads = 8
# 提高刷新脏页数量和合并插入数量，改善磁盘IO处理能力，根据自己的磁盘IOPS能力调整
# 把以前的built-in文件格式Antelope改为Barracudainnodb_file_format = Barracuda
# 脏页的调整，从以前的25改为90，这个值可在70--90之间选取innodb_max_dirty_pages_pct = 90
# 事务日志redo log的调整，从以前的256M改为1024Minnodb_log_file_size = 1024
# 采用独立表空间innodb_file_per_table = 1
重启MySQL服务生效：[root@db_fb05 mysql-5.1.62]# service mysqld restartShutting down MySQL. SUCCESS!Starting MySQL.. SUCCESS![root@db_fb05 mysql-5.1.62]#
二、升级具体步骤
升级前有一个重要参数需要注意：innodb_fast_shutdown升级前要关闭这个功能(为什么要关请参考手册)：(root:opdba.com:Sat Dec 1 18:14:48 2012)[(none)]> show variables like '%fast%';+----------------------+-------+| Variable_name | Value |+----------------------+-------+| innodb_fast_shutdown | 1 |+----------------------+-------+1 row in set (0.00 sec)
(root:opdba.com:Sat Dec 1 18:35:20 2012)[(none)]> set global innodb_fast_shutdown=0;Query OK, 0 rows affected (0.00 sec)
(root:opdba.com:Sat Dec 1 18:35:43 2012)[(none)]> show variables like '%fast%';+----------------------+-------+| Variable_name | Value |+----------------------+-------+| innodb_fast_shutdown | 0 |+----------------------+-------+1 row in set (0.00 sec)
1.停止当前MySQL服务service mysqld stop
2.链接到新MySQL目录cd /opt/webserver/unlink mysqlln -sv mysql-5.5.34-linux2.6-x86_64 mysql
3.启动服务service mysqld start
4.执行更新程序升级/opt/webserver/mysql/bin/mysql_upgradeLooking for 'mysql' as: /opt/webserver/mysql/bin/mysqlLooking for 'mysqlcheck' as: /opt/webserver/mysql/bin/mysqlcheckRunning 'mysqlcheck' with connection arguments: '--port=3306' '--socket=/data/mysql/mysql.sock'/opt/webserver/mysql/bin/mysqlcheck: Got error: 2002: Can't connect to local MySQL server through socket '/data/mysql/mysql.sock' (111) when trying to connectFATAL ERROR: Upgrade failed
出现上面错误是由于当前MySQL服务器的root用户设置了密码，mysql_upgrade 加上-p参数批量root用户密码即可：/opt/webserver/mysql/bin/mysql_upgrade -padminLooking for 'mysql' as: /opt/webserver/mysql/bin/mysqlLooking for 'mysqlcheck' as: /opt/webserver/mysql/bin/mysqlcheckRunning 'mysqlcheck' with connection arguments: '--port=3306' '--socket=/data/mysql/mysql.sock'Running 'mysqlcheck' with connection arguments: '--port=3306' '--socket=/data/mysql/mysql.sock'mysql.columns_priv OKmysql.db OKmysql.event OKmysql.func OKmysql.general_log OKmysql.help_category OKmysql.help_keyword OKmysql.help_relation OKmysql.help_topic OKmysql.host OKmysql.ndb_binlog_index OKmysql.plugin OKmysql.proc OKmysql.procs_priv OKmysql.proxies_priv OKmysql.servers OKmysql.slow_log OKmysql.tables_priv OKmysql.time_zone OKmysql.time_zone_leap_second OKmysql.time_zone_name OKmysql.time_zone_transition OKmysql.time_zone_transition_type OKmysql.user OKRunning 'mysql_fix_privilege_tables'...OK
出现上面信息就说明升级OK！查看下当前的版本：[root@db_fb010 ~]# /opt/webserver/mysql/bin/mysql -VLogging to file '/data/mysql/logs/query.log'/opt/webserver/mysql/bin/mysql Ver 14.14 Distrib 5.5.34, for linux2.6 (x86_64) using readline 5.1
mysql_upgrade命令实际执行了以下操作：mysqlcheck --all-databases --check-upgrade --auto-repairmysql < fix_priv_tablesmysqlcheck --all-databases --check-upgrade --fix-db-names --fix-table-names
5.存储过程问题修复从5.1升级至5.5后，发现存储过程不能用的，创建存储过程和查看存储过程状态，会报如下错：(root:opdba.com:Sat Dec 1 18:14:48 2012)[(none)]> show procedure status;
ERROR 1548 (HY000): Cannot load from mysql.proc. The table is probably corrupted
通过上述报错，立马查看两边表 proc 的状态发现：show create table proc\G------>在5.1中mysql.proc表的comment字段是char(64)：`sql_mode` set('REAL_AS_FLOAT','PIPES_AS_CONCAT','ANSI_QUOTES','IGNORE_SPACE','IGNORE_BAD_TABLE_OPTIONS','ONLY_FULL_GROUP_BY','NO_UNSIGNED_SUBTRACTION','NO_DIR_IN_CREATE','POSTGRESQL','ORACLE','MSSQL','DB2','MAXDB','NO_KEY_OPTIONS','NO_TABLE_OPTIONS','NO_FIELD_OPTIONS','MYSQL323','MYSQL40','ANSI','NO_AUTO_VALUE_ON_ZERO','NO_BACKSLASH_ESCAPES','STRICT_TRANS_TABLES','STRICT_ALL_TABLES','NO_ZERO_IN_DATE','NO_ZERO_DATE','INVALID_DATES','ERROR_FOR_DIVISION_BY_ZERO','TRADITIONAL','NO_AUTO_CREATE_USER','HIGH_NOT_PRECEDENCE','NO_ENGINE_SUBSTITUTION','PAD_CHAR_TO_FULL_LENGTH') NOT NULL DEFAULT '',
`comment` char(64) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL DEFAULT '',
但在5.5中应该是text：`comment` text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
于是把这个字段修改为text： ALTER TABLE proc MODIFY COLUMN comment text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL AFTER sql_mode;
再次运行OK...........
最后说明下测试环境：[root@db_fb010 ~]# cat /etc/issueCentOS release 6.3 (Final)Kernel \r on an \m
[root@db_fb010 ~]# getconf LONG_BIT64
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