Question

So I have read about pipelining, and multi/exec commands. But have not been able to answer this question. Can I use the results of operation A in operation B inside redis, as to not take them out of redis. Can this be done with Lua scripting? Do this be done naturally in redis? Can I map the results in a specific way?

Answer 1

Yes, you can with Scripting, with the limitation that it will not play nice with Redis Cluster (which is not released yet anyway).

Here is an example in Ruby, but you can do it in any language if your Redis client supports EVAL:

require "redis"
redis = Redis.new

redis.hset("foo","bar","baz")
redis.set("baz",42)

script = <<EOS
local k = redis.call("hget","foo",ARGV[1])
return redis.call("get",k)
EOS

puts redis.eval(script,keys:[],argv:["bar"])

This snippet prints 42.