MySQL5.6 默认参数改变一览表

Setting	Old	New	Notes
back_log	50	50 + ( max_connections / 5 ) capped at 900
binlog_checksum	NONE	CRC32	New variable in 5.6. 5.5 doesn't accept the checksums. Use NONE if you want to read binlog with 5.5 or on master if have replication slaves using 5.5.
binlog-row-event-max-size	1k	8k	no binlog_row_event_max_size variable, just the option form.
flush_time	1800	Windows changes from 1800 to 0	Was already 0 on other platforms
host_cache_size	128	128 + 1 for each of the first 500 max_connections + 1 for every 20 max_connections over 500, capped at 2000	New variable in 5.6
innodb_autoextend_increment	8	64	64 is 64 megabytes
innodb_buffer_pool_instances	0	8. On 32 bit Windows only, if innodb_buffer_pool_size is greater than 1300M, default is innodb_buffer_pool_size / 128M
innodb_concurrency_tickets	500	5000
innodb_file_per_table	0	1
innodb_log_file_size	5M	48M	InnoDB will change size to match my.cnf value. Also see innodb_log_compressed_pages and binlog_row_image
innodb_old_blocks_time	0	1000	1 second
innodb_open_files	300	300. If innodb_file_per_table is ON, higher of table_open_cache or 300
innodb_purge_batch_size	20	300
innodb_purge_threads	0	1
innodb_stats_on_metadata	on	off
join_buffer_size	128k	256k
max_allowed_packet	1M	4M
max_connect_errors	10	100
open_files_limit	0	5000	See Note 1
query_cache_size	0	1M
query_cache_type	ON/1	OFF/0
sort_buffer_size	2M	256k
sql_mode	none	NO_ENGINE_SUBSTITUTION	See later post about default my.cnf for STRICT_TRANS_TABLES
sync_master_info	0	10000	Recommend: master_info_repository=table
sync_relay_log	0	10000
sync_relay_log_info	0	10000	Recommend: relay_log_info_repository=table. Also see Replication Relay and Status Logs
table_definition_cache	400	400 + table_open_cache / 2, capped at 2000
table_open_cache	400	2000	Also see table_open_cache_instances
thread_cache_size	0	8 + max_connections/100, capped at 100

转自：

https://blogs.oracle.com/supportingmysql/entry/server_defaults_changes_in_mysql