mysql - 电源故障和mysql崩溃

Question

我已经将 MySql 与 InnoDb 引擎一起使用了一段时间，对性能非常满意。我有 10 个表，每秒更新两次。最近我停电了，如果不将 innodb_force_recovery 设置为至少 4，就无法重新启动数据库。但是当试图修复损坏的表时，数据库会再次崩溃。我尝试了优化、检查、分析等，但都导致崩溃。错误日志包含如下消息:

InnoDB:错误:第 570 页日志序列号 7289495InnoDB:在未来!当前系统日志序号5574939。

最终，在删除与特定表相关的所有文件后，我设法通过 mysqldump(innodb_force_recovery 为 6)转储了数据库。然后我重新安装了 xampp 并重新加载了转储。这让我重新启动并运行，只丢失了一张 table 。

我的问题是，一个损坏的表怎么会导致整个数据库崩溃？

有没有办法将这种情况再次发生的风险降到最低，是否有某种配置可以提高对电源故障的鲁棒性？我知道显而易见的答案是在单独的服务器上保留一个复制备份数据库，但仅仅处于开发的测试阶段，这似乎有点过分了。

这是我正在使用的配置文件。

# Example MySQL config file for small systems.
#
# This is for a system with little memory (<= 64M) where MySQL is only used
# from time to time and it's important that the mysqld daemon
# doesn't use much resources.
#
# You can copy this file to
# C:/xampp2/mysql/bin/my.cnf to set global options,
# mysql-data-dir/my.cnf to set server-specific options (in this
# installation this directory is C:/xampp2/mysql/data) or
# ~/.my.cnf to set user-specific options.
#
# In this file, you can use all long options that a program supports.
# If you want to know which options a program supports, run the program
# with the "--help" option.

# The following options will be passed to all MySQL clients
[client] 
# password       = your_password 
port            = 3306 
socket          = "C:/xampp2/mysql/mysql.sock"


# Here follows entries for some specific programs 

# The MySQL server
[mysqld]
port= 3306
socket = "C:/xampp2/mysql/mysql.sock"
basedir = "C:/xampp2/mysql" 
tmpdir = "C:/xampp2/tmp" 
datadir = "C:/xampp2/mysql/data"
pid_file = "mysql.pid"
# enable-named-pipe
key_buffer = 16M
max_allowed_packet = 1G
sort_buffer_size = 512K
net_buffer_length = 8K
read_buffer_size = 256K
read_rnd_buffer_size = 512K
myisam_sort_buffer_size = 8M
log_error = "mysql_error.log"

# Change here for bind listening
# bind-address="127.0.0.1" 
# bind-address = ::1          # for ipv6

# Where do all the plugins live
plugin_dir = "C:/xampp2/mysql/lib/plugin/" 

# Don't listen on a TCP/IP port at all. This can be a security enhancement,
# if all processes that need to connect to mysqld run on the same host.
# All interaction with mysqld must be made via Unix sockets or named pipes.
# Note that using this option without enabling named pipes on Windows
# (via the "enable-named-pipe" option) will render mysqld useless!
# 
# commented in by lampp security
#skip-networking
#skip-federated

# Replication Master Server (default)
# binary logging is required for replication
# log-bin deactivated by default since XAMPP 1.4.11
#log-bin=mysql-bin

# required unique id between 1 and 2^32 - 1
# defaults to 1 if master-host is not set
# but will not function as a master if omitted
server-id   = 1

# Replication Slave (comment out master section to use this)
#
# To configure this host as a replication slave, you can choose between
# two methods :
#
# 1) Use the CHANGE MASTER TO command (fully described in our manual) -
#    the syntax is:
#
#    CHANGE MASTER TO MASTER_HOST=<host>, MASTER_PORT=<port>,
#    MASTER_USER=<user>, MASTER_PASSWORD=<password> ;
#
#    where you replace <host>, <user>, <password> by quoted strings and
#    <port> by the master's port number (3306 by default).
#
#    Example:
#
#    CHANGE MASTER TO MASTER_HOST='125.564.12.1', MASTER_PORT=3306,
#    MASTER_USER='joe', MASTER_PASSWORD='secret';
#
# OR
#
# 2) Set the variables below. However, in case you choose this method, then
#    start replication for the first time (even unsuccessfully, for example
#    if you mistyped the password in master-password and the slave fails to
#    connect), the slave will create a master.info file, and any later
#    change in this file to the variables' values below will be ignored and
#    overridden by the content of the master.info file, unless you shutdown
#    the slave server, delete master.info and restart the slaver server.
#    For that reason, you may want to leave the lines below untouched
#    (commented) and instead use CHANGE MASTER TO (see above)
#
# required unique id between 2 and 2^32 - 1
# (and different from the master)
# defaults to 2 if master-host is set
# but will not function as a slave if omitted
#server-id       = 2
#
# The replication master for this slave - required
#master-host     =   <hostname>
#
# The username the slave will use for authentication when connecting
# to the master - required
#master-user     =   <username>
#
# The password the slave will authenticate with when connecting to
# the master - required
#master-password =   <password>
#
# The port the master is listening on.
# optional - defaults to 3306
#master-port     =  <port>
#
# binary logging - not required for slaves, but recommended
#log-bin=mysql-bin


# Point the following paths to different dedicated disks
#tmpdir = "C:/xampp2/tmp"
#log-update = /path-to-dedicated-directory/hostname

# Uncomment the following if you are using BDB tables
#bdb_cache_size = 4M
#bdb_max_lock = 10000

# Comment the following if you are using InnoDB tables
#skip-innodb
innodb_data_home_dir = "C:/xampp2/mysql/data"
innodb_data_file_path = ibdata1:10M:autoextend
innodb_log_group_home_dir = "C:/xampp2/mysql/data"
#innodb_log_arch_dir = "C:/xampp2/mysql/data"
## You can set .._buffer_pool_size up to 50 - 80 %
## of RAM but beware of setting memory usage too high
innodb_buffer_pool_size = 2G
innodb_additional_mem_pool_size = 16M
## Set .._log_file_size to 25 % of buffer pool size
innodb_log_file_size = 50M
innodb_log_buffer_size = 20M
innodb_flush_log_at_trx_commit = 2
innodb_lock_wait_timeout = 50
innodb_buffer_pool_instances = 4

## UTF 8 Settings
#init-connect=\'SET NAMES utf8\'
#collation_server=utf8_unicode_ci
#character_set_server=utf8
#skip-character-set-client-handshake
#character_sets-dir="C:/xampp2/mysql/share/charsets"

[mysqldump]
quick
max_allowed_packet = 16M

[mysql]
no-auto-rehash
# Remove the next comment character if you are not familiar with SQL
#safe-updates

[isamchk]
key_buffer = 20M
sort_buffer_size = 20M
read_buffer = 2M
write_buffer = 2M

[myisamchk]
key_buffer = 20M
sort_buffer_size = 20M
read_buffer = 2M
write_buffer = 2M

[mysqlhotcopy]
interactive-timeout

Answer 1

InnoDB 在数据一致性方面非常保守。如果它捕获到任何意外情况(错误的校验和、 header 值等)，它会故意崩溃以避免损坏数据。

如何“将再次发生这种情况的风险降到最低”？

最好是保持 innodb_flush_log_at_trx_commit、doublewrite 等的安全默认值。互联网上充满了关于“如何使 MySQL 更快”的轻率建议，但它附带价格，你知道。