svoid indexRandomConceptField(Concepts cc default db_mainConcepts(), Class<? extends Concept> c) {
  S field = or(first(conceptFields(c)), "_dummy");
  print("Indexing " + c + "." + field);
  indexConceptField(cc, c, field);
  assertTrue("Concept class indexed", isConceptClassIndexed(cc, c));
  time { print("Got " + nConcepts(countConcepts(cc, c))); }
}