jokull/supabase/migrations/20240409210612_scheduled-jo...

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-- downloads data async into the http response table.
select
cron.schedule(
'download-bus-data',
'5 seconds',
$$
select gather_bus_data();
$$
);
-- copies data into a more permanent tabe/more useful format. note:
-- supabase has an issue where you cannot delete these triggers
-- directly, but a cascading delete of the trigger function also
-- removes the trigger itself.
CREATE FUNCTION copy_to_raw_table() RETURNS trigger LANGUAGE plpgsql AS $$
BEGIN
-- NOTE: the http_response sequence resets on DB restart, so there
-- is potential for old responses to have duplicated ids. we use a
-- constraint to only update newer entries (within the last 30
-- seconds). this should make accidentally overwriting older data
-- with newer values difficult. The API also provides a
-- lastUpdated value. we require that raw.created is at or after
-- that value to be updated.
update raw_bus_positions raw
set response_json = NEW.content::jsonb,
response_status = NEW.status_code
where raw.request_id = NEW.id
-- fairly generous constraint to account for long requests.
and raw.created >= (NEW.created - '30 seconds'::interval)
and raw.created >= (NEW.content::jsonb->'data'->'BusLocationByRoute'->>'lastUpdate')::timestamptz
and raw.response_json is null;
RETURN NULL; -- this is an AFTER trigger
END;
$$;
CREATE CONSTRAINT TRIGGER copy_http_response
AFTER INSERT ON net._http_response
DEFERRABLE INITIALLY DEFERRED
FOR EACH ROW
EXECUTE FUNCTION copy_to_raw_table();