Time zones are regional values that are offset (or displaced) from the universal coordinated time (UTC). The presence or absence of a time zone in a data type is referred to as implicit or explicit in the Teradata Database.
- Explicit: 2025-02-01 15:00:00-08:00 (Time zone offset is -08:00.)
- Implicit: 2025-02-01 15:00:00 (No time zone offset, system assumes one.)
When moving data between environments that have different time zone settings, the timestamp can be interpreted differently depending on the system's default time zone. How Teradata Fabric handles the date, time, and timestamp depends on the database settings in the initiating and target systems.
- Data type used (TIMESTAMP WITH TIME ZONE versus TIMESTAMP)
- System configuration of the TimeDateWZControl flag
- The session or user's default time zone
Teradata Fabric example: a Hadoop system was set to UTC+03:00 while Vantage had TimeDateWZControl = 0 (disabled), meaning timestamps were interpreted as UTC. This mismatch caused failures in pushdown queries because the same timestamp was interpreted differently in each system.
Solution: Use explicit time zones across systems by enabling the TIMESTAMP WITH TIME ZONE data type to avoid any confusion.
Explicit
Explicit means the time zone offset is specified and stored with the UTC value. Teradata Fabric receives and transfers the time in UTC format with the specified time zone offset. Therefore, the query time is represented correctly, regardless of the target's' local time zone.
For example, if an initiating system time is 15:00:00 UTC with a local time of 07:00:00 Pacific (an 8-hour offset behind UTC), both the initiating and target systems display 15:00:00-08:00:00, leaving no room for confusion as to the query time.
In other words: UTC (15:00/3pm) - Offset (-8 hours) = 7am Pacific (local) time results in the timestamp 15:00:00-08:00 on both the initiating and target systems.
| Initiator system time | Time Teradata Fabric sends | Target receives | Target system displays |
|---|---|---|---|
| 15:00:00-08:00 UTC-Pacific offset |
15:00:00-08:00 | 15:00:00-08:00 | 15:00:00-08:00 UTC-offset of initiator |
Implicit
Implicit (system default) means there is no time zone offset specified, and time is determined by enabling or disabling the TimeDateWZControl setting.
When TimeDateWZControl is enabled (system default), the time on the target system is represented as the default local time but is adjusted to the actual query time from the initiating system.
For example, if the initiating system time is 15:00:00 UTC and the target system is Pacific time (an 8-hour offset behind UTC), the target system displays the timestamp as 07:00:00. This is the correct time of the query from the initiating system adjusted to display as the time on the target system.
In other words: UTC (15:00/3pm) - Offset (-8 hours) = 7 am Pacific (local) time results in an adjusted timestamp of 07:00:00 for the target's local timezone.
When TimeDateWZControl is disabled, there is no offset conversion of the time and displays as if the time zone is the same. For instance, if the initiating system time is 15:00:00 UTC, Teradata Fabric on the target system receives and displays 15:00:00. This does not represent the correct query time based on the target's local time zone because there is no offset adjustment for the different time zones.
In other words: UTC 15:00:00 results in the timestamp 15:00:00.
In the following implicit table example, when the database flag TimeDateWZControl is disabled, the system assumes the timestamp is already in the local timezone and does not adjust it. Therefore, the timestamp 15:00:00 at the initiator is the same time shown on the target. When TimeDateWZControl is enabled, the 15:00:00 at the initiator is adjusted to reflect the target session's time zone, converted from UTC.
| Initiator system time | TimeDateWZControl | Time Teradata Fabric sends | Target receives | Target system displays | Adjusted for target time zone |
|---|---|---|---|---|---|
| 15:00:00 UTC local time |
Enabled | 15:00:00 | 15:00:00 | 07:00:00 UTC local time |
Yes |
| 15:00:00 UTC local time |
Disabled | 15:00:00 | 15:00:00 | 15:00:00 UTC local time |
No |