What is missing in the Redis scheme? How to solve the problem of binding order_id to courier_id?

In a Redis scheme, there is often a lack of an atomic mechanism to bind order_id to courier_id to prevent data desynchronization during parallel operations.

This problem can be solved using:

• Redis Transactions (MULTI/EXEC) for atomic updates of multiple keys.
• Lua scripts in Redis, which execute atomically and allow checking and establishing the link between order_id and courier_id in a single operation.

Example of a Lua script for binding:

local orderKey = KEYS[1]
local courierKey = KEYS[2]
local orderId = ARGV[1]
local courierId = ARGV[2]

if redis.call('exists', orderKey) == 0 then
  redis.call('set', orderKey, courierId)
  redis.call('set', courierKey, orderId)
  return 1
else
  return 0
end

This guarantees that the binding is created only if it does not already exist, preventing collisions.