feat: Optimization of spots not to miss any

internal/qso/qso.go

@@ -1809,6 +1809,28 @@ func (r *Repo) WorkedCountyKeys(ctx context.Context, keyFn func(state, cnty stri
 	return out, rows.Err()
 }
 
+// WorkedCallBandModeKeys returns the set of every worked "CALL|BAND|MODE" key
+// (all upper-cased), loaded in one pass. It backs the in-memory worked-index the
+// alert engine checks per cluster spot — a DB query per spot cannot keep up with
+// an FT8 skimmer firehose (and hammers a remote MySQL).
+func (r *Repo) WorkedCallBandModeKeys(ctx context.Context) (map[string]struct{}, error) {
+	rows, err := r.db.QueryContext(ctx,
+		`SELECT upper(callsign), upper(band), upper(mode) FROM qso WHERE callsign != ''`)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	out := make(map[string]struct{}, 4096)
+	for rows.Next() {
+		var c, b, m string
+		if err := rows.Scan(&c, &b, &m); err != nil {
+			return nil, err
+		}
+		out[c+"|"+b+"|"+m] = struct{}{}
+	}
+	return out, rows.Err()
+}
+
 // WorkedPOTARefs returns the set of POTA park references already worked
 // (upper-cased). A QSO's pota_ref may hold several comma-separated parks
 // (an n-fer); each is added separately.