Calendar Core

Apple Calendar — Local Data Reference

Database Location

$HOME/Library/Group Containers/group.com.apple.calendar/Calendar.sqlitedb

WAL mode — always accompanied by .sqlitedb-shm and .sqlitedb-wal. Reads work fine against the live database without locking.

DB="$HOME/Library/Group Containers/group.com.apple.calendar/Calendar.sqlitedb"
sqlite3 "$DB" "SELECT ..."

Critical: CoreData Epoch (NOT Unix Epoch)

All timestamps are seconds since January 1, 2001, not 1970. Convert in SQLite:

datetime(field + 978307200, 'unixepoch', 'localtime')

Convert current time to CoreData timestamp in bash:

NOW_CD=$(( $(date +%s) - 978307200 ))
FUTURE_CD=$(( $(date +%s) + N * 86400 - 978307200 ))

Critical: OccurrenceCache for Recurring Events

Never query CalendarItem.start_date directly for date-range queries. It only holds the original first occurrence. Future instances of recurring events only exist in OccurrenceCache.

Always use OccurrenceCache as the entry point for any time-windowed query.

occurrence_start_date is NULL for some recurring events — use COALESCE(occurrence_start_date, occurrence_date) for start time.

SQLite Schema

Key Tables

CalendarItem.status Values

• 0 — none / tentative
• 1 — confirmed
• 2 — cancelled (exclude these)

CalendarItem.invitation_status Values

• 0 — none (own events)
• 3 — pending invite (not yet accepted)

Store.type Values

• 0 — local
• 1 — local
• 5 — "Found in Mail" — always exclude (auto-created duplicates from email invites)

Participant.entity_type Values

• 7 — attendee
• 8 — organizer

Participant.status Values

• 0 — needs-action
• 1 — accepted
• 2 — declined
• 3 — tentative

Participant.role Values

• 0 — non-participant / unknown
• 1 — required
• 2 — optional

Recurrence.frequency Values

• 1 — daily
• 2 — weekly
• 3 — monthly
• 4 — yearly

Standard Exclusion Filters

Always apply:

WHERE ci.hidden = 0          -- exclude hidden events
  AND ci.status != 2         -- exclude cancelled events
  AND s.type != 5            -- exclude "Found in Mail" duplicates
  AND s.disabled = 0         -- active accounts only

Canonical Query Template

SELECT
  ci.ROWID as id,
  ci.summary as title,
  COALESCE(
    datetime(oc.occurrence_start_date + 978307200, 'unixepoch', 'localtime'),
    datetime(oc.occurrence_date + 978307200, 'unixepoch', 'localtime')
  ) as start_local,
  datetime(oc.occurrence_end_date + 978307200, 'unixepoch', 'localtime') as end_local,
  ci.all_day,
  ci.start_tz as timezone,
  COALESCE(l.title, '') as location,
  ci.conference_url,
  ci.has_attendees,
  ci.has_recurrences,
  ci.status,
  ci.invitation_status,
  c.title as calendar_name,
  s.name as account_name
FROM OccurrenceCache oc
JOIN CalendarItem ci ON oc.event_id = ci.ROWID
LEFT JOIN Calendar c ON ci.calendar_id = c.ROWID
LEFT JOIN Store s ON c.store_id = s.ROWID
LEFT JOIN Location l ON ci.location_id = l.ROWID
WHERE oc.occurrence_date >= NOW_CD
  AND oc.occurrence_date <= FUTURE_CD
  AND ci.hidden = 0
  AND ci.status != 2
  AND s.type != 5
  AND s.disabled = 0
GROUP BY ci.ROWID, date(oc.occurrence_date + 978307200, 'unixepoch', 'localtime')
ORDER BY oc.occurrence_date;

GROUP BY ci.ROWID, date(...) deduplicates multi-day spanning events that appear once per day in OccurrenceCache.

Fetching Attendees (On-Demand Per Event)

Only fetch attendees for specific events — never bulk join, it's slow:

SELECT email, entity_type, role, status
FROM Participant
WHERE owner_id = EVENT_ROWID
ORDER BY entity_type DESC, status;

Filter s.disabled = 0 to get only active accounts. Discover your active accounts with:

SELECT s.name, s.type, COUNT(*) as calendars
FROM Store s
JOIN Calendar c ON c.store_id = s.ROWID
WHERE s.type != 5 AND s.disabled = 0
GROUP BY s.ROWID
ORDER BY s.name;