Setting the file. One moment.
Skill 103 · Querying PostHog Data
Subchapter 103.62
references/person-property-modes.mdMarkdown2 KBView on GitHub
PostHog has two modes for how person.properties.* behaves when querying the events table.
The active mode is included in the project metadata.
When person-on-events is enabled, person properties are stored on each event at ingestion time. on the table returns the value as it was when the event was captured.
person.properties.XeventsargMin(person.properties.X, timestamp) returns the earliest value — useful for cohort assignmentargMax(person.properties.X, timestamp) returns the latest value for that time rangeperson.properties.X can place the same person in multiple groups if the value changed-- Correct: get the user's membership type at their first event each day
SELECT
distinct_id,
dateTrunc('day', timestamp) AS day,
argMin(person.properties.currentMembershipType, timestamp) AS membership_at_start_of_day
FROM events
WHERE event = '$pageview'
AND timestamp >= now() - INTERVAL 7 DAY
GROUP BY distinct_id, dayWhen person-on-events is disabled, person properties are joined at query time.
person.properties.X on the events table always returns the person’s current (latest) value.
argMin(person.properties.X, timestamp) and argMax(person.properties.X, timestamp) return the same value — they are no-ops for segmentationproperties.membershipType set via $set on the event itself)-- In query-time mode, this returns the CURRENT membership type for all events
-- It does NOT reflect what the type was when the event occurred
SELECT
person.properties.currentMembershipType AS current_type,
count() AS event_count
FROM events
WHERE event = '$pageview'
AND timestamp >= now() - INTERVAL 7 DAY
GROUP BY current_typeRegardless of mode, querying persons.properties.X directly (from the persons table, not via events) always returns the current value.
The project metadata in the system prompt indicates which mode is active. If you are unsure, ask the user whether their person properties change over time and whether they need historical values.