collaboration • Code Review Videos! • clocks, clock_cast, leap_seconds (https://youtu.be/WX3OmVu4lAs) • time_zone and time_zone_link (https://youtu.be/MODhhr7m-5s) • system_clock::now(), file_clock, leap second be added to the library: • tzdb • tzdb_list • time_zone • zoned_time • time_zone_link • ambiguous_local_time • nonexistent_local_time • …37 time_zone • Represents a “time zone” and all time zone transitions zone, whether it is during “daylight saving”, etc.38 zoned_time • Represents a pairing of a time_zone and a time_point (so a specific point in time in the context of a particular time zone). •

作用域 说明 autocommit GLOBAL \ SESSION 是否自动 Commit 事务 sql_mode GLOBAL \ SESSION 支持部分 MySQL SQL mode， time_zone GLOBAL \ SESSION 数据库所使用的时区 tx_isolation GLOBAL \ SESSION 事务隔离级别 系统变量 设置系统变量 全局范围值 会话范围值 TiDB 支持的 时区 TiDB 使用的时区由 time_zone 全局变量和 session 变量决定。 time_zone 的初始值是机器当前的系统时区 ‘SYSTEM’ 。 在运行过程中可以修改全局时区： 1. mysql> SET GLOBAL time_zone = timezone; TiDB 还可以通过设置 session 变量 time_zone 为每个连接维护各自的时区。默认条件下，这个值取的是全局 为每个连接维护各自的时区。默认条件下，这个值取的是全局 变量 time_zone 的值。修改 session 使用的时区： 1. mysql> SET time_zone = timezone; 查看当前使用的时区的值： 1. mysql> SELECT @@global.time_zone, @@session.time_zone; 设置 time_zone 的值的格式： ‘SYSTEM’ 表明使用系统时间 相对于 UTC

© 2012-2021 UCloud 优刻得 117/120 当前实例创建完成后，默认时区为UTC时间，如果⽤⼾需要CST时间，需要⼿动设置时区+8 SET time_zone = '+8:00'; SET GLOBAL time_zone ='+8:00'; 重新连接mysql即可⽣效 Q12:查看 查看TiDB创建索引的过程是否已经结束 创建索引的过程是否已经结束 通过“admin show ddl;”语句查看当前job的进度

Support The time zone in TiDB is decided by the global time_zone system variable and the ses- sion time_zone system variable. The default value of time_zone is SYSTEM. The actual time zone corresponding to System statement to set the global server time_zone value at runtime: SET GLOBAL time_zone = timezone; Each client has its own time zone setting, given by the session time_zone variable. Initially, the session session variable takes its value from the global time_zone variable, but the client can change its own time zone with this statement: SET time_zone = timezone; You can use the following statement to view the

Support The time zone in TiDB is decided by the global time_zone system variable and the ses- sion time_zone system variable. The default value of time_zone is SYSTEM. The actual time zone corresponding to System statement to set the global server time_zone value at runtime: SET GLOBAL time_zone = timezone; Each client has its own time zone setting, given by the session time_zone variable. Initially, the session session variable takes its value from the global time_zone variable, but the client can change its own time zone with this statement: SET time_zone = timezone; You can use the following statement to view the

Support The time zone in TiDB is decided by the global time_zone system variable and the ses- sion time_zone system variable. The default value of time_zone is SYSTEM. The actual time zone corresponding to System statement to set the global server time_zone value at runtime: SET GLOBAL time_zone = timezone; Each client has its own time zone setting, given by the session time_zone variable. Initially, the session session variable takes its value from the global time_zone variable, but the client can change its own time zone with this statement: SET time_zone = timezone; You can use the following statement to view the

Support The time zone in TiDB is decided by the global time_zone system variable and the ses- sion time_zone system variable. The default value of time_zone is SYSTEM. The actual time zone corresponding to System statement to set the global server time_zone value at runtime: SET GLOBAL time_zone = timezone; Each client has its own time zone setting, given by the session time_zone variable. Initially, the session session variable takes its value from the global time_zone variable, but the client can change its own time zone with this statement: SET time_zone = timezone; You can use the following statement to view the

Support The time zone in TiDB is decided by the time_zone system variable. You can set it at the session or global level. The default value of time_zone is SYSTEM. The actual time zone corresponding to @@session.time_zone, @@global.system_time_zone; 8.7.2 Set the time zone In TiDB, the value of the time_zone system variable can be set in one of the following formats: • SYSTEM (default value), which indicates SET GLOBAL time_zone = ${time-zone-value}; For example, set the global time zone to UTC: SET GLOBAL time_zone = 'UTC'; • Set the time zone in TiDB at the session level: SET time_zone = ${time-zone-value};

RESOURCE GROUP • DROP RESOURCE GROUP • RESOURCE GROUP RFC 8.7 时区支持 TiDB 使用的时区由 time_zone 全局变量和 session 变量决定。time_zone 的默认值是 System，System 对应的实 际时区在 TiDB 集群 bootstrap 初始化时设置。具体逻辑如下： • 优先使用 TZ 环境变量 • 作为系统时区。 在运行过程中可以修改全局时区： SET GLOBAL time_zone = timezone; TiDB 还可以通过设置 session 变量 time_zone 为每个连接维护各自的时区。默认条件下，这个值取的是全局变 量 time_zone 的值。修改 session 使用的时区： SET time_zone = timezone; 使用以下 SQL 语句查看当前全局时区、客户端时区和系统时区的值： 语句查看当前全局时区、客户端时区和系统时区的值： SELECT @@global.time_zone, @@session.time_zone, @@global.system_time_zone; 设置 time_zone 的值的格式： • ‘SYSTEM’ 表明使用系统时间 • 相对于 UTC 时间的偏移，比如 ‘+10:00’ 或者 ‘-6:00’ • 某个时区的名字，比如 ‘Europe/Helsinki’，‘US/Eastern’

RESOURCE GROUP • DROP RESOURCE GROUP • RESOURCE GROUP RFC 8.7 时区支持 TiDB 使用的时区由 time_zone 全局变量和 session 变量决定。time_zone 的默认值是 System，System 对应的实 际时区在 TiDB 集群 bootstrap 初始化时设置。具体逻辑如下： • 优先使用 TZ 环境变量 • 作为系统时区。 在运行过程中可以修改全局时区： SET GLOBAL time_zone = timezone; TiDB 还可以通过设置 session 变量 time_zone 为每个连接维护各自的时区。默认条件下，这个值取的是全局变 量 time_zone 的值。修改 session 使用的时区： SET time_zone = timezone; 使用以下 SQL 语句查看当前全局时区、客户端时区和系统时区的值： 语句查看当前全局时区、客户端时区和系统时区的值： SELECT @@global.time_zone, @@session.time_zone, @@global.system_time_zone; 设置 time_zone 的值的格式： • ‘SYSTEM’ 表明使用系统时间 • 相对于 UTC 时间的偏移，比如 ‘+10:00’ 或者 ‘-6:00’ • 某个时区的名字，比如 ‘Europe/Helsinki’，‘US/Eastern’