1 2Bug#25650399: DOWNGRADE FROM MYSQL 8.0 WITH WL#10128 TO 5.7 3WILL CRASH SERVER 4 5ALTER TABLE mysql.server_cost 6ADD COLUMN default_value FLOAT GENERATED ALWAYS AS (cost_name) VIRTUAL; 7ALTER TABLE mysql.engine_cost 8ADD COLUMN default_value FLOAT GENERATED ALWAYS AS (cost_name) VIRTUAL; 9FLUSH OPTIMIZER_COSTS; 10mysql.columns_priv OK 11mysql.db OK 12mysql.engine_cost OK 13mysql.event OK 14mysql.func OK 15mysql.general_log OK 16mysql.gtid_executed OK 17mysql.help_category OK 18mysql.help_keyword OK 19mysql.help_relation OK 20mysql.help_topic OK 21mysql.innodb_index_stats OK 22mysql.innodb_table_stats OK 23mysql.ndb_binlog_index OK 24mysql.plugin OK 25mysql.proc OK 26mysql.procs_priv OK 27mysql.proxies_priv OK 28mysql.server_cost OK 29mysql.servers OK 30mysql.slave_master_info OK 31mysql.slave_relay_log_info OK 32mysql.slave_worker_info OK 33mysql.slow_log OK 34mysql.tables_priv OK 35mysql.time_zone OK 36mysql.time_zone_leap_second OK 37mysql.time_zone_name OK 38mysql.time_zone_transition OK 39mysql.time_zone_transition_type OK 40mysql.user OK 41mtr.global_suppressions OK 42mtr.test_suppressions OK 43sys.sys_config OK 44SELECT * FROM mysql.server_cost; 45cost_name cost_value last_update comment 46disk_temptable_create_cost NULL # NULL 47disk_temptable_row_cost NULL # NULL 48key_compare_cost NULL # NULL 49memory_temptable_create_cost NULL # NULL 50memory_temptable_row_cost NULL # NULL 51row_evaluate_cost NULL # NULL 52SELECT * FROM mysql.engine_cost; 53engine_name device_type cost_name cost_value last_update comment 54default 0 io_block_read_cost NULL # NULL 55default 0 memory_block_read_cost NULL # NULL 56