code: def namedb_get_num_blockstack_ops_at( db, block_id ):
      
      cur = db.cursor()
  
      # preorders at this block
      preorder_count_rows_query = "SELECT COUNT(*) FROM preorders WHERE block_number = ?;"
      preorder_count_rows_args = (block_id,)
      
      num_preorders = namedb_select_count_rows(cur, preorder_count_rows_query, preorder_count_rows_args)
  
      # committed operations at this block
      query = "SELECT COUNT(*) FROM history WHERE block_id = ?;"
      args = (block_id,)
  
      rows_result = namedb_query_execute(cur, query, args)
  
      count = 0
      for r in rows_result:
          count = r['COUNT(*)']
          break
  
      log.debug("{} preorders; {} history rows at {}".format(num_preorders, count, block_id))
      return count + num_preorders
docs: Get the number of name/namespace/token operations that occurred at a particular block.