$lua = EOT
 local kws = {}
 local lrkws = {}
  local nkws = {}
  local kw_ids = {}
  local lr_ids = {}
  local n_ids = {}

  for kw in string.gmatch(KEYS[1], "[^|]+") do
   table.insert(kws, "kw:"..kw)
  end
  for kw in string.gmatch(KEYS[2], "[^|]+") do
   table.insert(lrkws, "lrkw:"..kw)
  end
  for kw in string.gmatch(KEYS[3], "[^|]+") do
   table.insert(nkws, "nkw:"..kw)
  end

  if #kws > 0 then
   kw_ids = redis.call('sinter', unpack(kws))
  end
  if #lrkws > 0 then
   lr_ids = redis.call('sinter', unpack(lrkws))
  end
  if #nkws > 0 then
   n_ids = redis.call('sinter', unpack(nkws))
  end
  local cache_key = ARGV[1]

  for _, v in ipairs(kw_ids) do
   redis.call('sadd', cache_key, v)
  end
  for _, v in ipairs(lr_ids) do
   redis.call('sadd', cache_key, v)
  end
  for _, v in ipairs(n_ids) do
   redis.call('sadd', cache_key, v)
  end
  redis.call('expire', cache_key, 600)
  return redis.call('scard', cache_key)
EOT;

 $ret = $redis->eval($lua, array("你好|謝謝", "", "hello", "cache_key"), 3);
 echo $ret;