-- Similar incidents: a signature per incident, so "has this happened before"
-- is an indexed equality instead of a search.
--
-- The signature is the alert name plus the group labels that identify WHAT is
-- broken, minus the ones that only say WHERE it happened to run this time
-- (instance, pod, ...). Two incidents with the same signature in the same team
-- are the same problem for a responder's purposes.
--
-- Computed in Go for new incidents (incidentSignature in incident_store.go).
-- The backfill below MUST produce the same string; keep the volatile list in
-- both places in step.
ALTER TABLE incidents ADD COLUMN signature TEXT NOT NULL DEFAULT '';

UPDATE incidents SET signature =
    COALESCE(NULLIF(group_labels->>'alertname', ''), title) || '|' ||
    COALESCE((
        SELECT string_agg(e.k || '=' || e.v, ',' ORDER BY e.k)
          FROM jsonb_each_text(incidents.group_labels) AS e(k, v)
         WHERE e.k <> 'alertname'
           AND e.k NOT IN ('instance', 'pod', 'pod_name', 'pod_ip', 'container', 'container_name', 'endpoint')
    ), '');

CREATE INDEX incidents_signature_idx ON incidents(team_id, signature, triggered_at DESC);