Allow events to be un-rejected (element-hq#2159)

* Allow un-rejecting an event later

* SQL

* Only un-reject, don't re-reject

* Clarify ambiguous column reference

Author: neilalexander

roomserver/storage/postgres/events_table.go

@@ -71,10 +71,10 @@ CREATE TABLE IF NOT EXISTS roomserver_events (
 `
 
 const insertEventSQL = "" +
-	"INSERT INTO roomserver_events (room_nid, event_type_nid, event_state_key_nid, event_id, reference_sha256, auth_event_nids, depth, is_rejected)" +
+	"INSERT INTO roomserver_events AS e (room_nid, event_type_nid, event_state_key_nid, event_id, reference_sha256, auth_event_nids, depth, is_rejected)" +
 	" VALUES ($1, $2, $3, $4, $5, $6, $7, $8)" +
-	" ON CONFLICT ON CONSTRAINT roomserver_event_id_unique" +
-	" DO NOTHING" +
+	" ON CONFLICT ON CONSTRAINT roomserver_event_id_unique DO UPDATE" +
+	" SET is_rejected = $8 WHERE e.is_rejected = FALSE" +
 	" RETURNING event_nid, state_snapshot_nid"
 
 const selectEventSQL = "" +

roomserver/storage/sqlite3/events_table.go

@@ -49,7 +49,8 @@ const eventsSchema = `
 const insertEventSQL = `
 	INSERT INTO roomserver_events (room_nid, event_type_nid, event_state_key_nid, event_id, reference_sha256, auth_event_nids, depth, is_rejected)
 	  VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
-	  ON CONFLICT DO NOTHING
+	  ON CONFLICT DO UPDATE
+	  SET is_rejected = $8 WHERE is_rejected = 0
 	  RETURNING event_nid, state_snapshot_nid;
 `