Part1:写在最前
提到MySQL升级，网上文章数之不尽，但大多数为老的版本，诸如5.1升级到5.5、5.5升级到5.6，今天给大家介绍下MySQL5.6升级到MySQL5.7版本的方法和注意事项。
Part2:升级方法
升级的方法一般有两类：
1.利用mysqldump来直接导出sql文件，导入到新库中，这种方法是最省事儿的，也是最保险的，缺点的话，也显而易见，大库的mysqldump费时费力。
2.直接替换掉mysql的安装目录和my.cnf，利用mysql_upgrade 来完成系统表的升级，这种方法需要备份原有的文件，但属于物理拷贝，速度较快。缺点的话，跨版本升级不推荐这么做，比如mysql5.1升级到mysql5.6,mysql5.5升级到mysql5.7等。
本文采用的是第二种方法升级。
Part3:环境
数据库软件目录：/usr/local/mysql
my.cnf位置：/etc/my.cnf
数据库data目录：/data/mysql
慢日志目录：/data/slowlog
Part1:MySQL5.6.25
[root@HE3 ~]# mysql -uroot -p Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 1 Server version: 5.6.25-log MySQL Community Server (GPL) Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> select version(); +------------+ | version() | +------------+ | 5.6.25-log | +------------+ 1 row in set (0.00 sec) mysql> use helei; Database changed mysql> show tables; +-----------------+ | Tables_in_helei | +-----------------+ | helei | +-----------------+ 1 row in set (0.00 sec)我这里用的是5.6.25版本作为待升级库，库中已经模拟和创建了数据库helei和表helei，用以之后验证升级。
Part2:备份
备份整体需要备份的是my.cnf、数据库安装目录、还有数据目录。
[root@HE3 ~]# /etc/init.d/mysqld stop
Shutting down MySQL.. SUCCESS!
[root@HE3 etc]# cp -rp my.cnf my_56_old.cnf
[root@HE3 local]# cp -rp mysql mysql_56_old
[root@HE3 ~]# rm -rf /usr/local/mysql
[root@HE3 data]# cp -rp mysql/ mysql_56_old
这里我直接采用cp的方式来进行。
Part3:替换
1.替换/etc/my.cnf为mysql5.7的my.cnf
[root@HE3 ~]#vi /etc/my.cnf [client] port=3306 socket=/tmp/mysql.sock default-character-set=utf8 [mysql] no-auto-rehash default-character-set=utf8 [mysqld] port=3306 character-set-server=utf8 socket=/tmp/mysql.sock basedir=/usr/local/mysql datadir=/data/mysql explicit_defaults_for_timestamp=true lower_case_table_names=1 back_log=103 max_connections=3000 max_connect_errors=100000 table_open_cache=512 external-locking=FALSE max_allowed_packet=32M sort_buffer_size=2M join_buffer_size=2M thread_cache_size=51 query_cache_size=32M #query_cache_limit=4M transaction_isolation=REPEATABLE-READ tmp_table_size=96M max_heap_table_size=96M ###***slowqueryparameters long_query_time=1 slow_query_log = 1 slow_query_log_file=/data/slowlog/slow.log ###***binlogparameters log-bin=mysql-bin binlog_cache_size=4M max_binlog_cache_size=8M max_binlog_size=1024M binlog_format=MIXED expire_logs_days=7 ###***relay-logparameters #relay-log=/data/3307/relay-bin #relay-log-info-file=/data/3307/relay-log.info #master-info-repository=table #relay-log-info-repository=table #relay-log-recovery=1 #***MyISAMparameters key_buffer_size=16M read_buffer_size=1M read_rnd_buffer_size=16M bulk_insert_buffer_size=1M #skip-name-resolve ###***master-slavereplicationparameters server-id=$SERVERID slave-skip-errors=all #***Innodbstorageengineparameters innodb_buffer_pool_size=512M innodb_data_file_path=ibdata1:10M:autoextend #innodb_file_io_threads=8 innodb_thread_concurrency=16 innodb_flush_log_at_trx_commit=1 innodb_log_buffer_size=16M innodb_log_file_size=512M innodb_log_files_in_group=2 innodb_max_dirty_pages_pct=75 innodb_buffer_pool_dump_pct=50 innodb_lock_wait_timeout=50 innodb_file_per_table=on innodb_buffer_pool_dump_at_shutdown=1 innodb_buffer_pool_load_at_startup=1 sql_mode=STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION [mysqldump] quick max_allowed_packet=32M [myisamchk] key_buffer=16M sort_buffer_size=16M read_buffer=8M write_buffer=8M [mysqld_safe] open-files-limit=8192 log-error=/data/mysql/error.log pid-file=/data/mysql/mysqld.pid2.解压新版mysql
[root@HE3 ~]# tar xvf mysql-5.7.15-linux-glibc2.5-x86_64.tar.gz
[root@HE3 ~]# mv mysql-5.7.15-linux-glibc2.5-x86_64 /usr/local/mysql
[root@HE3 ~]# chown -R mysql. /usr/local/mysql
3.替换新版mysqld启动脚本
[root@HE3 ~]# cp /usr/local/mysql/support-files/mysql.server /etc/init.d/mysqld
cp: overwrite `/etc/init.d/mysqld'? y
Part1:启动
[root@HE3 ~]# /etc/init.d/mysqld start Starting MySQL..... SUCCESS! [root@HE3 ~]# ps -ef|grep mysql root 26467 1 0 20:30 pts/2 00:00:00 /bin/sh /usr/local/mysql/bin/mysqld_safe --datadir=/data/mysql --pid-file=/data/mysql/HE3.pid mysql 27197 26467 4 20:30 pts/2 00:00:01 /usr/local/mysql/bin/mysqld --basedir=/usr/local/mysql --datadir=/data/mysql --plugin-dir=/usr/local/mysql/lib/plugin --user=mysql --log-error=/data/mysql/error.log --open-files-limit=8192 --pid-file=/data/mysql/HE3.pid --socket=/tmp/mysql.sock --port=3306 root 27235 25656 0 20:31 pts/2 00:00:00 grep mysql这里虽然启动成功了，但error日志里能捕捉到很多错误信息，因为没有升级字典，诸如：
2016-10-20T03:30:27.375466Z 0 [ERROR] Native table 'performance_schema'.'events_statements_summary_by_program' has the wrong structure 2016-10-20T03:30:27.375506Z 0 [ERROR] Native table 'performance_schema'.'events_transactions_current' has the wrong structure 2016-10-20T03:30:27.375536Z 0 [ERROR] Native table 'performance_schema'.'events_transactions_history' has the wrong structure 2016-10-20T03:30:27.375568Z 0 [ERROR] Native table 'performance_schema'.'events_transactions_history_long' has the wrong structure 2016-10-20T03:30:27.375598Z 0 [ERROR] Native table 'performance_schema'.'events_transactions_summary_by_thread_by_event_name' has the wrong structurePart2:系统表升级
1.升级数据字典
[root@HE3 ~]# /usr/local/mysql/bin/mysql_upgrade -uroot -pMANAGER mysql_upgrade: [Warning] Using a password on the command line interface can be insecure. Checking if update is needed. Checking server version. Running queries to upgrade MySQL server. Checking system database. mysql.columns_priv OK mysql.db OK mysql.engine_cost OK mysql.event OK mysql.func OK mysql.general_log OK mysql.gtid_executed OK mysql.help_category OK mysql.help_keyword OK mysql.help_relation OK mysql.help_topic OK mysql.innodb_index_stats OK mysql.innodb_table_stats OK mysql.ndb_binlog_index OK mysql.plugin OK mysql.proc OK mysql.procs_priv OK mysql.proxies_priv OK mysql.server_cost OK mysql.servers OK mysql.slave_master_info OK mysql.slave_relay_log_info OK mysql.slave_worker_info OK mysql.slow_log OK mysql.tables_priv OK mysql.time_zone OK mysql.time_zone_leap_second OK mysql.time_zone_name OK mysql.time_zone_transition OK mysql.time_zone_transition_type OK mysql.user OK Upgrading the sys schema. Checking databases. helei.helei OK sys.sys_config OK Upgrade process completed successfully. Checking if update is needed.2.重启实例再次检查error日志
[root@HE3 ~]# /etc/init.d/mysqld restart
Shutting down MySQL.. SUCCESS!
Starting MySQL. SUCCESS!
3.请保证一些路径的设置和以前的my.cnf一致，如果设置错误，很可能导致启动不了数据库
[ERROR] Could not use /data/slowlog/slow.log for logging
我这里是由于慢日志的位置和老的mysql5.6路径不一致，创建/data/slowlog即可，这里要仔细看报错，然后根据报错来发现和解决问题。
Part1:输入用户名密码检查结果
[root@HE3 ~]# mysql -uroot -p Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 2 Server version: 5.7.15-log MySQL Community Server (GPL) Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> select version(); +------------+ | version() | +------------+ | 5.7.15-log | +------------+ 1 row in set (0.00 sec)Part2:验证库和表是否有丢失
mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | helei | | mysql | | performance_schema | | sys | | test | +--------------------+ 6 rows in set (0.00 sec)升级5.7后，我们会发现多了一个sys库，这个库有很多的功能，以后再给大家慢慢介绍~
——总结——
MySQL升级有多种方式，但无论采用何种方式，都要做好备份和回滚的准备，以避免升级失败所带来的损失。由于笔者的水平有限，编写时间也很仓促，文中难免会出现一些错误或者不准确的地方，不妥之处恳请读者批评指正。
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