一、简介
MySQL的启动配置文件。
通过mysqld的--defaults-file参数来配置，默认的读取顺序(mysql --help来查看)：
Default options are read from the following files in the given order: /etc/my.cnf /etc/mysql/my.cnf /usr/local/mysql/etc/my.cnf ~/.my.cnf
可见，是按/etc/my.cnf-->/etc/mysql/my.cnf-->/usr/local/mysql/etc/my.cnf-->~/.my.cnf的顺序来读取配置。如果这几个配置文件都有同一个参数，则遵循覆盖原则。
二、配置示例
如下是某公司的MySQL 5.6配置my.cnf，谨供参考。
# [mysqld] # GENERAL # character_set_server = utf8mb4 collation_server = utf8mb4_general_ci user = mysql default_storage_engine = InnoDB port = 3306 socket = /usr/local/mysql/multi/3306/socket/mysql.sock pid_file = /usr/local/mysql/multi/3306/pid/mysql.pid # MyISAM # key_buffer_size = 128M myisam_sort_buffer_size = 8M read_rnd_buffer_size = 262144 # SAFETY # back_log = 50 bind-address = 0.0.0.0 innodb_strict_mode = 1 max_allowed_packet = 32M max_connect_errors = 1000000 interactive_timeout = 900 wait_timeout = 900 skip_grant_tables = 0 skip_name_resolve = 1 host_cache_size = 0 sql_mode = TRADITIONAL sysdate_is_now = 1 transaction_isolation = REPEATABLE-READ explicit_defaults_for_timestamp = 1 # DATA STORAGE # basedir = /usr/local/mysql datadir = /usr/local/mysql/multi/3306/data tmpdir = /usr/local/mysql/multi/3306/tmp # BINARY LOGGING # binlog_cache_size = 1M binlog_format = ROW expire_logs_days = 1 max_binlog_size = 512M max_binlog_cache_size = 4G log_bin = /usr/local/mysql/multi/3306/binlog/mysql-bin log_bin_index = /usr/local/mysql/multi/3306/binlog/mysql-bin.index sync_binlog = 0 innodb_support_xa = 1 master-info-repository = TABLE # REPLICATION # log_slave_updates = 0 read_only = 0 relay_log = /usr/local/mysql/multi/3306/binlog/relay-bin relay_log_index = /usr/local/mysql/multi/3306/binlog/relay-bin.index server_id = 26759 slave_skip_errors = ALL slave_net_timeout = 60 relay-log-info-repository = TABLE slave_compressed_protocol = ON # CACHES AND LIMITS # max_connections = 5000 max_heap_table_size = 128M tmp_table_size = 128M open_files_limit = 65535 query_cache_limit = 1M query_cache_min_res_unit = 4096 query_cache_size = 0 query_cache_type = 0 join_buffer_size = 1M read_buffer_size = 1M sort_buffer_size = 1M table_definition_cache = 4096 table_open_cache = 4000 thread_cache_size = 1000 # INNODB # innodb_autoextend_increment = 8 innodb_buffer_pool_instances = 8 innodb_buffer_pool_size = 1G innodb_buffer_pool_load_at_startup = ON innodb_buffer_pool_dump_at_shutdown = ON innodb_data_file_path = ibdata1:1024M:autoextend innodb_fast_shutdown = 1 innodb_file_format = Barracuda innodb_file_format_max = Barracuda innodb_file_per_table = 1 innodb_force_recovery = 0 innodb_flush_log_at_trx_commit = 0 innodb_flush_method = O_DIRECT innodb_lock_wait_timeout = 50 innodb_log_buffer_size = 8M innodb_log_file_size = 512M innodb_log_files_in_group = 2 innodb_open_files = 10000 innodb_purge_threads = 4 innodb_read_io_threads = 8 innodb_write_io_threads = 8 innodb_show_verbose_locks = 1 innodb_sync_spin_loops = 30 innodb_thread_concurrency = 24 innodb_print_all_deadlocks = 1 # LOGGING # general_log = 0 general_log_file = /usr/local/mysql/multi/3306/log/mysql-general.log log_error = /usr/local/mysql/multi/3306/log/mysql-error.log log_queries_not_using_indexes = 1 long_query_time = 1 slow_query_log = 1 slow_query_log_file = /usr/local/mysql/multi/3306/log/mysql-slow.log # enforce_gtid_consistency = 0 gtid_mode = OFF