On this page

Show all

Help Center/ Data Lake Insight/ FAQs/ Flink Jobs/ Flink SQL/ Why Is the RDS Database Time Read by a Flink Opensource SQL Job Different from RDS Database Time?

Why Is the RDS Database Time Read by a Flink Opensource SQL Job Different from RDS Database Time?

Updated on 2023-05-19 GMT+08:00

View PDF

The time zone of a database is improperly set. Generally, there is a 13-hour difference.

Run the following statement in the RDS database:

show variables like '%time_zone%'

The execution result if as follows:

time_zone indicates the database time zone. The value SYSTEM indicates the system time of the database server ('system_time_zone'). The value of the system time zone is CST. Therefore, the database time zone is CST.
system_time_zone indicates the time zone of the server where the database is located. The server is a computer.
If the default time zone of the computer where the local database is located is China Standard Time, the value of system_time_zone is CST.

The real problem here is that time_zone is set to SYSTEM and system_time_zone is set to CST for an RDS for MySQL database. In the MySQL database, CST is China Standard Time (UTC+8), but it is Central Standard Time (USA) (UTC-5) in Java. Flink TaskManager is a Java process that reads the time zone set in the JDBC driver code of the MySQL database through TimeZone.getTimeZone(canonicalTimezone). The method gets time zone CST (UTC+8), but the actual time zone is CST (UTC-5).

Solution (either of the following method)

Do not set the value of time_zone to SYSTEM. You can set it to, for example, +08:00.
Add the time zone to jdbcUrl.
For example, jdbc:mysql://localhost:3306/test?serverTimezone=Asia/Shanghai.

Parent topic: Flink SQL

Feedback

Was this page helpful?

Helpful Not helpful

Provide feedback

Thank you very much for your feedback. We will continue working to improve the documentation.

The system is busy. Please try again later.

Which of the following issues have you encountered?

Content is inconsistent with the product UI

Unclear descriptions

Lack of examples or code

Incorrect steps

Can't find what I need

Lack of best practices

Feedback (optional)

0/500

Select at least one type of issue, and enter your comments or suggestions.

Enter a maximum of 500 characters.

Submit Cancel