versioned_docs/version-1.2/advanced/time-zone.md

---
{
    "title": "Time zone",
    "language": "en"
}
---

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# Time zone

Doris supports multiple time zone settings

## Noun Interpretation

* FE: Frontend, the front-end node of Doris. Responsible for metadata management and request access.
* BE: Backend, Doris's back-end node. Responsible for query execution and data storage.

## Basic concepts

There are multiple time zone related parameters in Doris

* `system_time_zone`:

When the server starts, it will be set automatically according to the time zone set by the machine, which cannot be modified after setting.

* `time_zone`:

Server current time zone, set it at session level or global level.

## Specific operations

1. `SHOW VARIABLES LIKE '% time_zone%'`

    View the current time zone related configuration

2. `SET time_zone = 'Asia/Shanghai'`

    This command can set the session level time zone, which will fail after disconnection.

3. `SET global time_zone = 'Asia/Shanghai'`
   
    This command can set time zone parameters at the global level. The FE will persist the parameters and will not fail when the connection is disconnected.

### Impact of time zone

Time zone setting affects the display and storage of time zone sensitive values.

It includes the values displayed by time functions such as `NOW()` or `CURTIME()`, as well as the time values in `SHOW LOAD` and `SHOW BACKENDS` statements.

However, it does not affect the `LESS THAN VALUE` of the time-type partition column in the `CREATE TABLE` statement, nor does it affect the display of values stored as `DATE/DATETIME` type.

Functions affected by time zone:

* `FROM_UNIXTIME`: Given a UTC timestamp, return the date and time of the specified time zone, such as `FROM_UNIXTIME(0)`, return the CST time zone: `1970-01-08:00`.

* `UNIX_TIMESTAMP`: Given a specified time zone date and time, return UTC timestamp, such as CST time zone `UNIX_TIMESTAMP('1970-01 08:00:00')`, return `0`.

* `CURTIME`: Returns the datetime of specified time zone.

* `NOW`: Returns the specified date and time of specified time zone.

* `CONVERT_TZ`: Converts a date and time from one specified time zone to another.

## Restrictions

Time zone values can be given in several formats, case-insensitive:

* A string representing UTC offset, such as '+10:00' or '-6:00'.

* Standard time zone formats, such as "Asia/Shanghai", "America/Los_Angeles"

* Abbreviated time zone formats such as MET and CTT are not supported. Because the abbreviated time zone is ambiguous in different scenarios, it is not recommended to use it.

* In order to be compatible with Doris and support CST abbreviated time zone, CST will be internally transferred to "Asia/Shanghai", which is Chinese standard time zone.

## Time zone format list

[List of TZ database time zones](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones)