oracle time settings

Oracle is one of the most popular enterprise-level databases in the world. Its time settings are crucial to the normal operation of the database and the accuracy of the data. In Oracle, time involves two aspects: database time and operating system time. This article will introduce how to set the time of the Oracle database to ensure the accuracy and correctness of the data.

1. Time zone setting

Before setting the time of the Oracle database, we first need to understand the concept of time zone. Time zones refer to the time standards adopted by regions at different locations on the earth. There are certain time differences between different time zones. Therefore, when setting the time of the Oracle database, we need to ensure that the time zone setting of the server where the Oracle database is located is correct.

Under Linux system, we can use the following command to query and set the current time zone:

Query the current time zone:

$ timedatectl status

Settings Time zone:

$ timedatectl set-timezone Asia/Shanghai

Under Windows system, we can change the time zone in the "Date and Time" setting of the control panel.

No matter which operating system it is under, in order to ensure that the time of the Oracle database is correct, we need to ensure that the time zone of the operating system is consistent with the time zone of the Oracle database. We can use the following command to query/change the time zone of the Oracle database:

Query the time zone of the current database:

SELECT DBTIMEZONE FROM DUAL;

Change the time zone of the database:

ALTER DATABASE SET TIME_ZONE='Asia/Shanghai';

2. Time synchronization

In an Oracle database running between multiple servers, we need to ensure the time between servers It's synchronous. Even when running on a single server, in order to avoid data errors caused by clock deviation, we need to ensure that the time of the operating system and the Oracle database are synchronized.

Under Linux systems, we can use the following command to enable the Network Time Protocol (NTP) client to synchronize the server's time with an external time server:

$ yum install ntp
$ systemctl enable ntpd
$ systemctl start ntpd

Under Windows system, we can enable the "Internet Time" option in the "Date and Time" settings of the control panel to synchronize time with an external time server.

3. Database time check

After we complete the time zone and time synchronization settings, we can check whether the time settings of the Oracle database are correct. We can check the database time and operating system time using the following command:

Query the time and date of the current database:

SELECT TO_CHAR(SYSDATE,'YYYY-MM-DD HH24:MI:SS' ) FROM DUAL;

Query the time and date of the current operating system:

SELECT TO_CHAR(SYSTIMESTAMP,'YYYY-MM-DD HH24:MI:SS.FF') FROM DUAL;

If the time settings of the Oracle database and the operating system are consistent, the query results should be the same or very close. If there are some minor differences, which may be caused by different query methods and formats, we can consider using a more precise time query method.

4. Summary

In the Oracle database, setting the time correctly is crucial to the accuracy and correctness of the data. Therefore, when setting up the Oracle database, we should ensure that the time zone settings of the operating system and the Oracle database are consistent, and ensure that the time between servers is synchronized. Finally, we can use the database time check command to ensure that the Oracle database's time settings are correct.

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