How to Save Time

This isn't a productivity talk. It's a survey of some idiosyncrasies related to persisting date/time values to a database.

Transcript

1. 
 How to Save Time Joel Clermont
 @jclermont
2. Productivity
3. ISO8601
4. Date time values are tricky • Date math • Leap years/seconds • Daylight Saving Time • Time Zones • Many more . . . https://infiniteundo.com/post/25326999628/falsehoods- programmers-believe-about-time
5. Approach 1 Everything is local
6. Everything is local 2018-11-06T09:05:23
7. Everything is local Pro: super easy, no thought/effort Con: What if you have users in a different time zone?
8. Approach 2 Local plus time zone offset
9. Local plus offset 2018-11-06T09:05:23-06:00
10. Local plus offset Pro: can convert to other time zones Con: Not consistent, lots of tz values
11. Approach 3 Always store UTC
12. Always store UTC 2018-11-06T15:05:23Z 2018-11-06T15:05:23+00:00
13. Always store UTC Pro: able to convert, consistent Con: ?? Is there an unsolved problem?
14. Problem Politicians can break your code
16. What if the time zone rules change?
17. https://www.timeanddate.com/news/time/
18. https://www.timeanddate.com/news/time/
19. Approach 4 Future dates as wall time + tz name
20. Future as wall + tz name 2019-11-06T12:00:00 America/Sao_Paulo
21. Future as wall + tz name Pro: TZ rules can change Con: New time zones? God help you
22. Questions? @jclermont
23. Thank you! @jclermont