max / goingson
| 1 | -- Events carry their own timezone semantics instead of inheriting the reading |
| 2 | -- machine's zone. |
| 3 | -- |
| 4 | -- Before this, an event was a bare UTC instant and every recurrence rule was |
| 5 | -- expanded against `system_tz()` at read time. That made the schedule a property |
| 6 | -- of the machine doing the reading: the same database opened in Denver and in |
| 7 | -- Lisbon produced different local times AND different weekdays, because a rule |
| 8 | -- anchored at 01:00 UTC is Monday in Denver and Tuesday in Lisbon. |
| 9 | -- |
| 10 | -- Three kinds, following iCalendar's distinction: |
| 11 | -- |
| 12 | -- relative civil wall clock, no zone. "06:00 wherever I am." Follows the |
| 13 | -- user; this is what a personal routine (wake, gym, errands) means. |
| 14 | -- local civil wall clock + an IANA zone. "10:00 America/Denver", correct |
| 15 | -- across that zone's DST whoever is reading. iCalendar's TZID. |
| 16 | -- absolute a fixed UTC instant. A moment, displayed in whatever zone you are |
| 17 | -- in. What every row was implicitly treated as until now. |
| 18 | -- |
| 19 | -- Storage: for `relative` and `local` the civil columns are the truth and |
| 20 | -- `start_time`/`end_time` hold a materialized UTC projection, kept so every |
| 21 | -- existing range query, index, and ORDER BY keeps working untouched. For |
| 22 | -- `absolute` the UTC columns are the truth and the civil ones stay NULL. |
| 23 | -- |
| 24 | -- The materialization is derived, never authoritative. For `local` it is |
| 25 | -- deterministic (civil + zone). For `relative` it depends on where the user |
| 26 | -- currently is, so it is recomputed when the system zone changes -- which is |
| 27 | -- also why the civil columns, not the UTC ones, are what a sync peer should |
| 28 | -- trust when the two disagree. |
| 29 | -- |
| 30 | -- Deliberately behaviour-preserving: every existing row becomes `absolute`, |
| 31 | -- which is precisely how it was already being treated. Reclassifying a routine |
| 32 | -- as `relative` is a separate, deliberate act on the user's own data, not |
| 33 | -- something a migration should guess for every machine that runs it. |
| 34 | |
| 35 | events ADD COLUMN tz_kind TEXT NOT NULL DEFAULT 'absolute'; |
| 36 | events ADD COLUMN timezone TEXT; |
| 37 | events ADD COLUMN start_local TEXT; |
| 38 | events ADD COLUMN end_local TEXT; |
| 39 | |
| 40 | -- Partial index: the zone-change recompute pass touches only relative rows, and |
| 41 | -- on a calendar of mostly fixed appointments that is a small slice of the table. |
| 42 | NOT EXISTS idx_events_tz_kind ON events(tz_kind) WHERE tz_kind != 'absolute'; |
| 43 |