controlplane, storage: an indexable request predicate; each dropped report is traced

Review: COALESCE(resolved_at, created_at) < ? cannot use the index on
created_at; resolved_at < ? OR (resolved_at IS NULL AND created_at < ?)
can. And a peer whose service report the sweep drops is a decision about
that peer, so it leaves a debug line with its ID; the count stays at info.

Author: aojea

internal/controlplane/node_gc.go

@@ -181,6 +181,7 @@ func (s *Server) pruneCatalog(now time.Time) {
 	for peerID := range snap {
 		if _, ok := keep[peerID]; !ok {
 			delete(s.catalog, peerID)
+			logger.Debugw("Dropped service report of a node no longer admitted", "peer_id", peerID)
 			dropped++
 		}
 	}

internal/storage/sql_store.go

@@ -1124,15 +1124,17 @@ func (s *SQLStore) DeleteSilentBootstrapNodes(ctx context.Context, before, ephem
 
 // DeleteStaleEnrollmentRequests implements Store.
 func (s *SQLStore) DeleteStaleEnrollmentRequests(ctx context.Context, before, ephemeralBefore time.Time) (int64, error) {
-	res, err := s.db.ExecContext(ctx, s.rebind(`DELETE FROM enrollment_requests WHERE COALESCE(resolved_at, created_at) < ?`), before.UnixMilli())
+	// The OR form, rather than COALESCE over the two columns, lets an index
+	// on either column serve the predicate.
+	res, err := s.db.ExecContext(ctx, s.rebind(`DELETE FROM enrollment_requests WHERE resolved_at < ? OR (resolved_at IS NULL AND created_at < ?)`), before.UnixMilli(), before.UnixMilli())
 	if err != nil {
 		return 0, err
 	}
 	regular, err := res.RowsAffected()
 	if err != nil {
 		return 0, err
 	}
-	res, err = s.db.ExecContext(ctx, s.rebind(`DELETE FROM enrollment_requests WHERE COALESCE(resolved_at, created_at) < ? AND token_id IN (SELECT id FROM bootstrap_tokens WHERE ephemeral = ?)`), ephemeralBefore.UnixMilli(), true)
+	res, err = s.db.ExecContext(ctx, s.rebind(`DELETE FROM enrollment_requests WHERE (resolved_at < ? OR (resolved_at IS NULL AND created_at < ?)) AND token_id IN (SELECT id FROM bootstrap_tokens WHERE ephemeral = ?)`), ephemeralBefore.UnixMilli(), ephemeralBefore.UnixMilli(), true)
 	if err != nil {
 		return regular, err
 	}