# Understanding Tag Historian Timestamps in PostgreSQL

**URL:** <https://forum.inductiveautomation.com/t/understanding-tag-historian-timestamps-in-postgresql/63663>\
**Category:** Ignition\
**Created:** [August 31, 2022, 11:42pm UTC](https://forum.inductiveautomation.com/t/understanding-tag-historian-timestamps-in-postgresql/63663 "2022-08-31T23:42:53Z")\
**Posts on this page:** 1\
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**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [November 10, 2023, 9:37pm UTC](https://forum.inductiveautomation.com/t/understanding-tag-historian-timestamps-in-postgresql/63663/9 "2023-11-10T21:37:52Z")

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> [@tyler.bennett](#):
>
> it gives me time in my gateway timezone (not UTC).

No, it is **printing** the time in the gateway timezone, but the underlying java object is timezoneless.

I recommend you read this topic about datetime objects in Ignition in general:

> [@System.date.now Timezone](https://forum.inductiveautomation.com/t/system-date-now-timezone/72478/8):
>
> The java.util.Date() object returned from any of Ignition's date and time functions, whether expression or script, Has No TimeZone! It is always UTC milliseconds. It is converted to a zoned format when converted to string. So, if converted to a string in the gateway, it will use the gateway timezone. If in Perspective, in the browser, it will use Perspective's client timezone. If you convert to string yourself, in a script or expression in Perspective, since those run in the gateway, you w…

Then consider that PostgreSQL uses the **same technique** for its `timestamp with time zone` datatype (aka `timestamptz`), except that the underlying storage format is UTC **microseconds** instead of **milliseconds** (and a non-epoch zero point).

So, `timestamptz` in PostgreSQL is fundamentally _timezoneless_, and is only shown with a timezone when converted to a string in an execution context that has a time zone. Same when parsing a string into a timestamp--uses the execution context's timezone, then stores/computes with the UTC microseconds.

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