TZADD
Adds time: seconds/minutes/hours are absolute, days/weeks/months/years are DST-aware calendar units
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When to use it
When should I use TZADD with days instead of adding 86400 seconds?
Use days when you want the same wall-clock time the next day regardless of DST. Adding 1 day across a DST boundary gives 23 or 25 real hours so the clock reads the same time, while adding 86400 seconds always moves exactly 86400 seconds forward.
What is the difference between adding hours and adding days in TZADD?
Hours, minutes, and seconds are absolute and operate at the UTC level, so adding 24 hours always advances the instant by exactly 24 hours. Days are calendar-aware and respect DST crossings in the stored zone, so adding 1 day lands on the same wall-clock time the following day.
What does the policy parameter control in TZADD?
The policy parameter controls how TZADD resolves the result when arithmetic lands in a DST gap or overlap — for example, choosing whether to snap forward or backward when the computed local time is ambiguous or non-existent.
Use cases
Calculate a meeting reminder 90 minutes before a zoned event
Advance a financial settlement date by one month
Used in
operations · finance · logistics
Syntax
TZADD(zoned,amount,unit,[policy])