Redis cluster uses Lua script. Lua script can also be used for different slots

In the project , Need to use lua Script operation redis cluster In the multiple key, But not the same slot I will make a mistake , For example, the following test3、test6 In the same node, But it's not the same slot.redis Use lua Scripts can be like this redis-cli -a xxxxx--eval demo.lua key1 key2 , val1 val2

[email protected]:~/redis-cluster$ redis-cli -p 16380 -c
192.168.88.7:6379> set test3 3333
-> Redirected to slot [13026] located at 192.168.88.3:6379
OK
192.168.88.6:6379> set test5 3333
-> Redirected to slot [4644] located at 192.168.88.5:6379
OK
192.168.88.5:6379> set test6 3333
-> Redirected to slot [8775] located at 192.168.88.3:6379
OK
192.168.88.3:6379> cluster keyslot test3
(integer) 13026
192.168.88.3:6379> cluster keyslot test6
(integer) 8775
192.168.88.3:6379>

adopt key Pass in

Generally in redis cluster Use in lua Script , You'll come across (error) CROSSSLOT Keys in request don't hash to the same slot

[email protected]:~/test$ cat get.lua
local key1 = KEYS[1]
local key1 = KEYS[2]

local value1 = redis.call("GET", key1)
local value2 = redis.call("GET", key2)

return {
    value1, value2}
[email protected]:~/test$  redis-cli -p 16380 -c --eval get.lua test3 test6
(error) CROSSSLOT Keys in request don't hash to the same slot

adopt value Pass in

In the official instructions ,redis Use lua Scripts are limited to one node The use of , But here is clearly the same node, But I can't use , But if we change the script to the following

[email protected]:~/test$ cat get.lua
local key1 = ARGV[1]
local key2 = ARGV[2]

local value1 = redis.call("GET", key1)
local value2 = redis.call("GET", key2)

return {
    value1, value2}
[email protected]:~/test$ redis-cli -p 16380 -c --eval get.lua  , test6 test3
1) "3333"
2) "3333"

This will solve .

summary

It should be according to KEY When it comes in ,redis In order to prevent key Not in the same node On , Yes key Conduct slot Judge , If it's not the same slot I'm going straight back , But it supports the same node Of ,** As long as we know what we need to do key To classify , The same node Of key adopt value Pass in , Can be in lua For the same node Of key operation .** In our design redis cluster When , Is to know every node Of slot Of , Every key Of solt The following calculations can be used

192.168.88.3:6379> cluster keyslot test3
(integer) 13026

We just need to judge first slot In a certain range , Belong to a node, Batch operation can be carried out .