说明：5.6、5.7默认启动占用内存400多M，如果是vps等小内存应用，mysql内存占用率明显偏高,将会导致崩溃，mysql会自动停止。 编辑/etc/my.cnf文件在[mysqld]下增加或修改如下参数
performance_schema_max_table_instances = 200
table_definition_cache = 100
table_open_cache = 100这个三个参数，调低值后内存能明显减小，现在mysql使用内存约60MB左右，就大大降低默认使用的内存。
进一步调整参数
innodb_buffer_pool_size=2M这个三个参数可以调小。 再进一步调整： mysql 5.6默认启用performance_schema，占用很多内存，可以禁用。
mysql5.7 about 40M
performance_schema = off
完整配置文件如下，内存占用到22M
我的mysql配置如下，如果你使用的centos6 64位，并且是yum安装的（一键脚本)可以自己按照如下照抄，我的是centos6 64位系统
先ssh登录服务器或VPS，在vi /etc/my.cnf
# For advice on how to change settings please see # http://dev.mysql.com/doc/refman/5.6/en/server-configuration-defaults.html [mysqld] character_set_server=utf8 # # Remove leading # and set to the amount of RAM for the most important data # cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%. # innodb_buffer_pool_size = 128M # # Remove leading # to turn on a very important data integrity option: logging # changes to the binary log between backups. # log_bin # # Remove leading # to set options mainly useful for reporting servers. # The server defaults are faster for transactions and fast SELECTs. # Adjust sizes as needed, experiment to find the optimal values. # join_buffer_size = 128M # sort_buffer_size = 2M # read_rnd_buffer_size = 2M datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock #symbolic-links=0 skip-external-locking key_buffer_size = 8M 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 = 240K #innodb_use_native_aio = 0innodb_buffer_pool_size=2Mperformance_schema = offperformance_schema_max_table_instances=50 table_definition_cache=50 table_open_cache=32 max_connections=50 max_user_connections=35 wait_timeout=10 interactive_timeout=15 long_query_time=5 # Disabling symbolic-links is recommended to prevent assorted security risks symbolic-links=0 # Recommended in standard MySQL setup sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES [mysqld_safe] log-error=/var/log/mysqld.log pid-file=/var/run/mysqld/mysqld.pid
默认值如下：
performance_schema_max_table_instances 12500
table_definition_cache 1400
table_open_cache 2000
正文完