MYSQL 5.7 无法修改max_allowed_packet参数?

环境:
CentOS 7
MySQL 5.7

问题:在my.cnf文件中修改max_allowed_packet后重启不生效,在mysql 中查看始终没变?
该如何修改max_allowed_packet参数。

1回答

大张猥大张猥  数据库管理员 , 上海
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[修改mysql配置中my.conf中max_allowed_packet变量] mysql根据配置文件会限制server接受的数据包大小。 有时候大的插入和更新会受max_allowed_packet 参数限制,导致写入或者更新失败。 查看目前配置 show VARIABLES like '%max_allowed_packet%'; 显示的结果为: +--------...显示全部

[修改mysql配置中my.conf中max_allowed_packet变量]

mysql根据配置文件会限制server接受的数据包大小。

有时候大的插入和更新会受max_allowed_packet 参数限制,导致写入或者更新失败。

查看目前配置

show VARIABLES like '%max_allowed_packet%';

显示的结果为:

+--------------------+---------+

| Variable_name | Value |

+--------------------+---------+

| max_allowed_packet | 1048576 |

+--------------------+---------+

以上说明目前的配置是:1M

修改方法

1、修改配置文件 (详情见下文 配置步骤 )

可以编辑my.cnf来修改(windows下my.ini),在[mysqld]段或者mysql的server配置段进行修改。

max_allowed_packet = 20M

如果找不到my.cnf可以通过

mysql --help | grep my.cnf

去寻找my.cnf文件。

linux下该文件在/etc/下。

2、在mysql命令行中修改

在mysql 命令行中运行

set global max_allowed_packet = 2*1024*1024*10

然后退出命令行,重启mysql服务,再进入。

show VARIABLES like '%max_allowed_packet%';

查看下max_allowed_packet是否编辑成功

配置步骤

1、首先查看mysql安装目录下support-files文件夹下是否有my-default.cnf这个文件

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localhost:etc qingclass$ pwd
/usr/local/mysql/support-files
sun:support-files sun$ ll
total 48
-rw-r--r--  1 root  wheel    773  3  4 21:40 magic
-rwxr-xr-x  1 root  wheel    894  3  4 22:27 mysql-log-rotate*
-rwxr-xr-x  1 root  wheel  10585  3  4 22:27 mysql.server*
-rwxr-xr-x  1 root  wheel   1061  3  4 22:27 mysqld_multi.server*

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如果有,就好办了,直接转移到/etc下,并且修改名字为my.cnf

2、如果没有则需要自己创建一个文件。

localhost:etc qingclass$ sudo vim my.cnf   #会打开创建一个新的文件,将下边的内容复制进去

复制代码

复制代码

# 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.
#
# MySQL programs look for option files in a set of
# locations which depend on the deployment platform.
# You can copy this option file to one of those
# locations. For information about these locations, see:
# http://dev.mysql.com/doc/mysql/en/option-files.html
#
# 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]
default-character-set=utf8
#password   = your_password
port        = 3306
socket      = /tmp/mysql.sock

# Here follows entries for some specific programs

# The MySQL server
[mysqld]
#解决only_full_group_by的问题
#sql_mode=STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION

default-storage-engine=INNODB
character-set-server=utf8
collation-server=utf8_general_ci
port        = 3306
socket      = /tmp/mysql.sock
skip-external-locking
key_buffer_size = 16K
max_allowed_packet = 1M
table_open_cache = 4
sort_buffer_size = 64K
read_buffer_size = 256K
read_rnd_buffer_size = 256K
net_buffer_length = 2K
thread_stack = 128K

# 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
# (using the "enable-named-pipe" option) will render mysqld useless!
#
#skip-networking
server-id   = 1

# Uncomment the following if you want to log updates
#log-bin=mysql-bin

# binary logging format - mixed recommended
#binlog_format=mixed

# Causes updates to non-transactional engines using statement format to be
# written directly to binary log. Before using this option make sure that
# there are no dependencies between transactional and non-transactional
# tables such as in the statement INSERT INTO t_myisam SELECT * FROM
# t_innodb; otherwise, slaves may diverge from the master.
#binlog_direct_non_transactional_updates=TRUE

# Uncomment the following if you are using InnoDB tables
#innodb_data_home_dir = /usr/local/mysql/data
#innodb_data_file_path = ibdata1:10M:autoextend
#innodb_log_group_home_dir = /usr/local/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 = 16M
#innodb_additional_mem_pool_size = 2M
# Set .._log_file_size to 25 % of buffer pool size
#innodb_log_file_size = 5M
#innodb_log_buffer_size = 8M
#innodb_flush_log_at_trx_commit = 1
#innodb_lock_wait_timeout = 50

[mysqldump]
quick
max_allowed_packet = 16M

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

[myisamchk]
key_buffer_size = 8M
sort_buffer_size = 8M

[mysqlhotcopy]
interactive-timeout

修改 mysqldump 和 mysqld 中修改max_allowed_packet变量退出保存

3、修改配置文件权限

chmod 664 /etc/my.cnf

4、重启mysql

5、登录mysql服务器 选择库,执行导入source /Users/qingclass/Downloads/sale_shared_revenue.sql

收起
 2019-12-04
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xylhldy系统工程师, 成都麦柯

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  • 发布时间:2019-12-01
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  • 问题浏览:2248
  • 最近回答:2019-12-04