Starting May 30, 2021, new ApsaraDB RDS for MySQL instances use the UTC time zone of the instance's region as the default time zone, instead of the system time zone of the underlying server.
Background
Before May 30, 2021, the default_time_zone parameter defaulted to SYSTEM, which used the system time zone of the server hosting the instance. When TIMESTAMP columns were queried frequently, this could cause serious performance issues.
To prevent these issues, Alibaba Cloud changed the default value of default_time_zone for new instances from SYSTEM to the UTC time zone of the region where the instance is deployed.
This change affects the TIMESTAMP data type only. The DATETIME type is not affected. For details about how MySQL handles these types differently, see The DATE, DATETIME, and TIMESTAMP types.
Effective time
May 30, 2021
This change applies to instances created on or after this date. Existing instances retain their original default_time_zone setting.
Action required for existing instances
If an existing instance still uses SYSTEM as the default_time_zone value, update it to match the UTC time zone of the instance's region to avoid potential performance issues.
Log on to the ApsaraDB RDS console and change the default_time_zone parameter value. For instructions, see Modify the parameters of an ApsaraDB RDS for MySQL instance.