set @@default_week_format = 4; select week('2020-02-02'), @@default_week_format, week('2020-02-02'); week('2020-02-02') @@default_week_format week('2020-02-02') 6 4 6 set @@default_week_format = default; set @@tidb_current_ts=1; Error 1238 (HY000): Variable 'tidb_current_ts' is a read only variable set @@last_plan_from_binding='123'; Error 1238 (HY000): Variable 'last_plan_from_binding' is a read only variable set @@last_plan_from_cache='123'; Error 1238 (HY000): Variable 'last_plan_from_cache' is a read only variable set @@global.collation_server=utf8mb4_general_ci; show global variables like 'collation_server'; Variable_name Value collation_server utf8mb4_general_ci show global variables like 'collation_server'; Variable_name Value collation_server utf8mb4_general_ci show variables like 'collation_server'; Variable_name Value collation_server utf8mb4_general_ci set @@global.collation_server=default; set @@global.tidb_memory_usage_alarm_ratio=1; select @@global.tidb_memory_usage_alarm_ratio; @@global.tidb_memory_usage_alarm_ratio 1 set @@global.tidb_memory_usage_alarm_ratio=0; select @@global.tidb_memory_usage_alarm_ratio; @@global.tidb_memory_usage_alarm_ratio 0 set @@global.tidb_memory_usage_alarm_ratio=0.7; select @@global.tidb_memory_usage_alarm_ratio; @@global.tidb_memory_usage_alarm_ratio 0.7 set @@global.tidb_memory_usage_alarm_ratio=1.1; Level Code Message Warning 1292 Truncated incorrect tidb_memory_usage_alarm_ratio value: '1.1' select @@global.tidb_memory_usage_alarm_ratio; @@global.tidb_memory_usage_alarm_ratio 1 set @@global.tidb_memory_usage_alarm_ratio=-1; Level Code Message Warning 1292 Truncated incorrect tidb_memory_usage_alarm_ratio value: '-1' select @@global.tidb_memory_usage_alarm_ratio; @@global.tidb_memory_usage_alarm_ratio 0 set @@session.tidb_memory_usage_alarm_ratio=0.8; Error 1229 (HY000): Variable 'tidb_memory_usage_alarm_ratio' is a GLOBAL variable and should be set with SET GLOBAL set @@global.tidb_memory_usage_alarm_keep_record_num=1; select @@global.tidb_memory_usage_alarm_keep_record_num; @@global.tidb_memory_usage_alarm_keep_record_num 1 set @@global.tidb_memory_usage_alarm_keep_record_num=100; select @@global.tidb_memory_usage_alarm_keep_record_num; @@global.tidb_memory_usage_alarm_keep_record_num 100 set @@global.tidb_memory_usage_alarm_keep_record_num=0; Level Code Message Warning 1292 Truncated incorrect tidb_memory_usage_alarm_keep_record_num value: '0' select @@global.tidb_memory_usage_alarm_keep_record_num; @@global.tidb_memory_usage_alarm_keep_record_num 1 set @@global.tidb_memory_usage_alarm_keep_record_num=10001; Level Code Message Warning 1292 Truncated incorrect tidb_memory_usage_alarm_keep_record_num value: '10001' select @@global.tidb_memory_usage_alarm_keep_record_num; @@global.tidb_memory_usage_alarm_keep_record_num 10000 set @@global.tidb_memory_usage_alarm_keep_record_num=default; set @@global.tidb_memory_usage_alarm_ratio=default; DROP TABLE IF EXISTS t_sel_in_share; CREATE TABLE t_sel_in_share (id int DEFAULT NULL); insert into t_sel_in_share values (11); select * from t_sel_in_share lock in share mode; Error 1235 (42000): function LOCK IN SHARE MODE has only noop implementation in tidb now, use tidb_enable_noop_functions to enable these functions set @@tidb_enable_noop_functions = 1; select * from t_sel_in_share lock in share mode; id 11 DROP TABLE t_sel_in_share; set @@tidb_enable_noop_functions = default; set tidb_enable_table_partition=off; show warnings; Level Code Message Warning 1105 tidb_enable_table_partition is always turned on. This variable has been deprecated and will be removed in the future releases set global tidb_enable_table_partition=off; show warnings; Level Code Message Warning 1105 tidb_enable_table_partition is always turned on. This variable has been deprecated and will be removed in the future releases show variables like 'tidb_enable_table_partition'; Variable_name Value tidb_enable_table_partition ON show global variables like 'tidb_enable_table_partition'; Variable_name Value tidb_enable_table_partition ON set tidb_enable_list_partition=on; show warnings; Level Code Message Warning 1681 tidb_enable_list_partition is deprecated and will be removed in a future release. set tidb_enable_list_partition=off; Error 1105 (HY000): tidb_enable_list_partition is now always on, and cannot be turned off show warnings; Level Code Message Warning 1681 tidb_enable_list_partition is deprecated and will be removed in a future release. Error 1105 tidb_enable_list_partition is now always on, and cannot be turned off show variables like 'tidb_enable_list_partition'; Variable_name Value tidb_enable_list_partition ON set global tidb_enable_list_partition=on; show global variables like 'tidb_enable_list_partition'; Variable_name Value tidb_enable_list_partition ON set tidb_enable_list_partition=1; show variables like 'tidb_enable_list_partition'; Variable_name Value tidb_enable_list_partition ON set @@foreign_key_checks=0; CREATE TABLE address ( id bigint(20) NOT NULL AUTO_INCREMENT, user_id bigint(20) NOT NULL, PRIMARY KEY (id), CONSTRAINT FK_7rod8a71yep5vxasb0ms3osbg FOREIGN KEY (user_id) REFERENCES waimaiqa.user (id), INDEX FK_7rod8a71yep5vxasb0ms3osbg (user_id) comment '' ) ENGINE=InnoDB AUTO_INCREMENT=30 DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci ROW_FORMAT=COMPACT COMMENT='' CHECKSUM=0 DELAY_KEY_WRITE=0; set @@foreign_key_checks=default; set @@tidb_sysdate_is_now=false; show variables like '%tidb_sysdate_is_now%'; Variable_name Value tidb_sysdate_is_now OFF set @@tidb_sysdate_is_now=true; show variables like '%tidb_sysdate_is_now%'; Variable_name Value tidb_sysdate_is_now ON set @@tidb_sysdate_is_now=default; select @@tidb_session_alias; @@tidb_session_alias set @@tidb_session_alias='alias123'; select @@tidb_session_alias; @@tidb_session_alias alias123 set @@tidb_session_alias='中文'; select @@tidb_session_alias; @@tidb_session_alias 中文 set @@tidb_session_alias='0123456789012345678901234567890123456789012345678901234567890123456789'; Level Code Message Warning 1292 Truncated incorrect tidb_session_alias value: '0123456789012345678901234567890123456789012345678901234567890123456789' select @@tidb_session_alias; @@tidb_session_alias 0123456789012345678901234567890123456789012345678901234567890123 set @@tidb_session_alias='中文测试1中文测试2中文测试3中文测试4中文测试5中文测试6中文测试7中文测试8中文测试9中文测试0中文测试a中文测试b中文测试c'; Level Code Message Warning 1292 Truncated incorrect tidb_session_alias value: '中文测试1中文测试2中文测试3中文测试4中文测试5中文测试6中文测试7中文测试8中文测试9中文测试0中文测试a中文测试b中文测试c' select @@tidb_session_alias; @@tidb_session_alias 中文测试1中文测试2中文测试3中文测试4中文测试5中文测试6中文测试7中文测试8中文测试9中文测试0中文测试a中文测试b中文测试 set @@tidb_session_alias='abc '; Level Code Message Warning 1292 Truncated incorrect tidb_session_alias value: 'abc ' select @@tidb_session_alias; @@tidb_session_alias abc set @@tidb_session_alias='abc 1'; Level Code Message Warning 1292 Truncated incorrect tidb_session_alias value: 'abc 1' select @@tidb_session_alias; @@tidb_session_alias abc set @@tidb_session_alias=''; select @@tidb_session_alias; @@tidb_session_alias set @@tidb_session_alias=default; set @@tidb_read_staleness='-5'; set @@tidb_read_staleness='-100'; set @@tidb_read_staleness='-5s'; Error 1232 (42000): Incorrect argument type to variable 'tidb_read_staleness' set @@tidb_read_staleness='foo'; Error 1232 (42000): Incorrect argument type to variable 'tidb_read_staleness' set @@tidb_read_staleness=''; set @@tidb_read_staleness='0'; set @@tidb_read_staleness=default; set global group_concat_max_len = 100; set @@session.group_concat_max_len = 50; show global variables where variable_name='group_concat_max_len'; Variable_name Value group_concat_max_len 100 show session variables where variable_name='group_concat_max_len'; Variable_name Value group_concat_max_len 50 select @@group_concat_max_len; @@group_concat_max_len 50 select @@global.group_concat_max_len; @@global.group_concat_max_len 100 select @@session.group_concat_max_len; @@session.group_concat_max_len 50 set @@group_concat_max_len = 1024; select @@group_concat_max_len; @@group_concat_max_len 1024 select @@global.group_concat_max_len; @@global.group_concat_max_len 100 select @@session.group_concat_max_len; @@session.group_concat_max_len 1024 set @@group_concat_max_len=1; Level Code Message Warning 1292 Truncated incorrect group_concat_max_len value: '1' select @@group_concat_max_len; @@group_concat_max_len 4 set @@group_concat_max_len = 18446744073709551616; Error 1232 (42000): Incorrect argument type to variable 'group_concat_max_len' set @@group_concat_max_len='hello'; Error 1232 (42000): Incorrect argument type to variable 'group_concat_max_len' set global group_concat_max_len = default; set @@session.group_concat_max_len = default;