Unix Epoch Time

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Unix Epoch Time is the standard internal way that Unix systems keep track of time. It's the time in seconds that has lapsed since January 1, 1970 UTC, adjusted for leap seconds.

Epoch Time as Notion card IDs

Some impressions about using epoch time as card IDs in Notion:

To get an impression about the length of epoch time (MySQL):

   unix_timestamp(now()) as now,   
   unix_timestamp("2023-02-18") as today,
   unix_timestamp("2023-01-18") as a_month_ago,
   unix_timestamp("2022-02-18") as a_year_ago,
   unix_timestamp("2021-02-18") as two_years_ago;

Output (formatting mine):

1645138800   # 1 year ago
1613602800   # 2 years ago

So, if I want to be able to distinguish timestamps within the last two years (for card-IDs in Notion), I need the last 8 figures:

45138800   # 1 year ago
13602800   # 2 years ago

When I want to distinguish timestamps within a month (or a bit longer), I would still need 7 digits

6745822   # Now
6674800   # "Today"
3996400   # A month ago

7 Digits isn't very practical. I could make it less, but the change increases that figures will be used double. More relevant: IDs won't be sequential anymore.

So actually, If all I care about, is unique IDs, and not about sequential numbers, it could be like this:

  • My largest Trello board has about 400 cards
  • With 3 digits, there is about 40% change that IDs get reused (isn't it?)
  • With 4 digits, this is about 4%
  • With 5 digits, this is aboout 0.4%.

A more realistic Trello board has about 70 cards:

  • With 3 digits: 7% change of double used IDs
  • With 4 digits: 0.7% change of double used IDs → Use 4 digits.

BTW: When using only 4 or 5 digits, you have an additional problem: ID's will cycle from 9xx to 0yy multiple times during a project. That can be confusing. But when it's only about having a 'rough identifier', 4 digits would do the job. Still messy, if you ask me.

See also