Redis cluster RTT

Question

We are currently using Redis as our data store. I am making a new section where we need to rank and paginate users. So i am thinking to use Sorted set for keeping rank and userid. And Hash for keeping user's profile data. It was brought to my attention by a colleague that we ll need to make many requests to redis to fetch users profile data using HGET. so Round trip time is going to be an issue. I was planning to use HMGET but After doing some research i found it may cause issues when Redis is clustered because Keys are stored in different redis nodes. I am using phpredis it has client side-sharding (I am having trouble understanding what that is).

i was thinking to do like this:

rank

zadd userRank 1 5
zadd userRank 2 2
zadd userRank 3 4
zadd userRank 4 3

userProfile

hset userProfile user:5 "{'userId':'5','name':'usera'}"
hset userProfile user:4 "{'userId':'4','name':'userb'}"
hset userProfile user:3 "{'userId':'3','name':'userc'}"
hset userProfile user:2 "{'userId':'2','name':'userb'}"

1) Will HMGET work normally in clustered Redis?

2) if not what can i do?

3) is there any better way to implement this?

Answer 1

1. HMGET should work in clustered Redis because it's only related to a single key. Each HMGET will be forwarded to the node that contains the key
2. /
3. It's not a good idea to store every serialized user in a hash you'll loose the ability to request/inc/dec some fiels.

Prefer:

hmset user:5 userId 5 name usera
hmset user:4 userId 4 name userb
hmset user:3 userId 3 name userc
hmset user:2 userId 2 name userb

Your ranking schema is ok. To retrieve & paginate between the top ranked users, just do a ZREVRANGEBYSCORE and then request each users.

Note: clustering is not the same as sharding.