如何获取与redis中的特定模式不匹配的键? [英] how to get keys which does not match a particular pattern in redis?

问题描述

在 Redis 中，keys user* 将打印所有以 user 开头的键.例如:

In Redis, keys user* will print all keys starting with user. For example:

keys user*
1) "user2"
2) "user1"

现在，我希望打印所有不以 user 开头的键.我怎么能这样做?

Now, I want all keys that don't start with user to be printed. How could I do that?

推荐答案

重要提示: 始终使用 SCAN 而不是(邪恶)<代码>密钥

IMPORTANT: always use SCAN instead of (the evil) KEYS

Redis 的模式匹配在功能上有些限制(请参阅 util.c) 并且不提供您寻求 ATM 的内容.也就是说，请考虑以下可能的路线:

Redis' pattern matching is somewhat functionally limited (see the implementation of stringmatchlen in util.c) and does not provide that which you seek ATM. That said, consider the following possible routes:

1. 扩展 stringmatchlen 以符合您的要求，可能将其作为 PR 提交.
2. 考虑您要尝试做什么 - 除非您对它们进行索引，否则获取键的子集总是效率低下的，请考虑跟踪所有非用户键的名称(例如在 Redis 集中).
3. 如果您真的坚持扫描整个键空间并匹配否定模式，那么实现这一点的一种方法是使用一点 Lua 魔法.

1. Extend stringmatchlen to match your requirements, possibly submitting it as a PR.
2. Consider what you're trying to do - fetching a subset of keys is always going to be inefficient unless you index them, consider tracking the names of all non-user keys (i.e.g. in a Redis Set) instead.
3. If you are really insistent on scanning the entire keyspace and match against negative patterns, one way to accomplish that is with a little bit of Lua magic.

考虑以下数据集和脚本:

Consider the following dataset and script:

127.0.0.1:6379> dbsize
(integer) 0
127.0.0.1:6379> set user:1 1
OK
127.0.0.1:6379> set use:the:force luke
OK
127.0.0.1:6379> set non:user a
OK

Lua(另存为 scanregex.lua):

local re = ARGV[1]
local nt = ARGV[2]

local cur = 0
local rep = {}
local tmp

if not re then
  re = ".*"
end

repeat
  tmp = redis.call("SCAN", cur, "MATCH", "*")
  cur = tonumber(tmp[1])
  if tmp[2] then
    for k, v in pairs(tmp[2]) do
      local fi = v:find(re) 
      if (fi and not nt) or (not fi and nt) then
        rep[#rep+1] = v
      end
    end
  end
until cur == 0
return rep

输出 - 第一次正则匹配，第二次补码:

Output - first time regular matching, 2nd time the complement:

foo@bar:~$ redis-cli --eval scanregex.lua , "^user"
1) "user:1"
foo@bar:~$ redis-cli --eval scanregex.lua , "^user" 1
1) "use:the:force"
2) "non:user"

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