-- 010_churn_metrics.sql
-- Fast-path BGP churn metrics, written by the obmp-churn-monitor service.
--
-- obmp-churn-monitor reads openbmp.parsed.unicast_prefix from Kafka with its
-- own consumer group and only COUNTS announcements/withdrawals per
-- (router, peer) -- no relational RIB maintenance. Because counting is far
-- cheaper than psql-app's per-route upserts, it stays real-time even when the
-- main ingestion pipeline lags minutes behind under a churn storm. This is the
-- decoupled "visibility path": it does not speed up the bulk DB write, it
-- guarantees churn visibility survives a storm the bulk pipeline cannot.

CREATE TABLE IF NOT EXISTS churn_metrics (
    ts         timestamptz NOT NULL DEFAULT now(),
    router_ip  inet,
    peer_ip    inet,
    peer_asn   bigint,
    adds       integer,
    dels       integer
);

SELECT create_hypertable('churn_metrics', 'ts', if_not_exists => TRUE);

CREATE INDEX IF NOT EXISTS idx_churn_ts        ON churn_metrics (ts DESC);
CREATE INDEX IF NOT EXISTS idx_churn_router_ts ON churn_metrics (router_ip, ts DESC);

DO $$ BEGIN
  PERFORM add_retention_policy('churn_metrics', INTERVAL '7 days');
EXCEPTION WHEN OTHERS THEN
  RAISE NOTICE 'churn_metrics retention policy not added: %', SQLERRM;
END $$;