MySQL8.0 新的默认参数值

PARAMETER/OPTION	OLD DEFAULT	NEW DEFAULT
SERVER
character_set_server	latin1	utf8mb4
collation_server	latin1_swedish_ci	utf8mb4_0900_ai_ci
explicit_defaults_for_timestamp	off	on
optimizer_trace_max_mem_size	16KB	1MB
validate_password_check_user_name	off	on
back_log	-1 (autosize) back_log = 50 + (max_connections / 5)	-1 (autosize) back_log = max_connections
max_allowed_packet	4194304 (4MB)	67108864 (64MB)
max_error_count	64	1024
event_scheduler	OFF	ON
table_open_cache	2000	4000
log_error_verbosity	3 (Notes)	2 (Warning)
INNODB
innodb_undo_tablespaces	0	2
innodb_undo_log_truncate	OFF	ON
innodb_flush_method	NULL	fsync (Unix), unbuffered (Windows)
innodb_autoinc_lock_mode	1 (consecutive)	2 (interleaved)
innodb_flush_neighbors	1 (enable)	0 (disable)
innodb_max_dirty_pages_pct_lwm	0 (%)	10 (%)
innodb_max_dirty_pages_pct	75 (%)	90 (%)
PERFORMANCE SCHEMA
performance-schema-instrument='wait/lock/metadata/sql/%=ON'	OFF	ON
performance-schema-instrument='memory/%=COUNTED'	OFF	COUNTED
performance-schema-consumer-events-transactions-current=ON	OFF	ON
performance-schema-consumer-events-transactions-history=ON	OFF	ON
performance-schema-instrument='transaction%=ON'	OFF	ON
REPLICATION
log_bin	off	on
server_id	0	1
log-slave-updates	off	on
expire_log_days	0	30
master-info-repository	FILE	TABLE
relay-log-info-repository	FILE	TABLE
transaction-write-set-extraction	OFF	XXHASH64
slave_rows_search_algorithms	INDEX_SCAN, TABLE_SCAN	INDEX_SCAN, HASH_SCAN

默认参数修改可以看出对字符集的增强，对Group replication的增强。

原文链接：

https://mysqlserverteam.com/new-defaults-in-mysql-8-0/