Data Modeling

Data Modeling in Redis

Redis is not relational. Data is stored as flat key-value pairs, and there are no JOINs. This requires thinking differently about your data model — choosing the right data structure and key naming strategy.

Key Naming Conventions

Use colons to separate namespaces in key names:

user:1              -- a single user (string or hash)
user:1:posts        -- a set or list of post IDs for user 1
post:42             -- a single post hash
post:42:comments    -- a list of comment IDs
index:posts:by_tag:redis  -- sorted set of posts tagged "redis"

This creates a consistent, readable key structure.

Storing Objects

Option 1: Hash (recommended for objects with many fields)

HSET user:1 name "Alice" email "alice@example.com" role "admin"
HGET user:1 name
HGETALL user:1

Option 2: JSON string (when you always need the whole object)

SET user:2 '{"name":"Bob","email":"bob@example.com"}'
GET user:2

One-to-Many Relationships

User → Posts: store post IDs in a set or sorted set:

HSET post:1 title "Hello Redis" author "alice" views "0"
HSET post:2 title "Redis Patterns" author "alice" views "0"
SADD user:1:posts "post:1" "post:2"

# Get Alice's posts
SMEMBERS user:1:posts

Tags and Inverted Indexes

# Tag posts by topic
SADD tag:redis "post:1" "post:2"
SADD tag:database "post:2" "post:3"

# Find posts tagged with both redis AND database
SINTER tag:redis tag:database

Rate Limiting Pattern

# Key = rate:userId:windowStart (minute-based)
SET rate:user123:api 0
INCR rate:user123:api
EXPIRE rate:user123:api 60

# Check before processing:
# If GET rate:user123:api > 100, reject

Session Storage

HSET session:abc123 user_id "42" role "admin" csrf_token "xyz"
EXPIRE session:abc123 3600
HGET session:abc123 user_id

Analytics with Sorted Sets

# Track product popularity (view count as score)
ZINCRBY trending:products 1 "product:laptop"
ZINCRBY trending:products 1 "product:laptop"
ZINCRBY trending:products 1 "product:phone"

# Get most popular
ZREVRANGE trending:products 0 4 WITHSCORES

Your Task

Model a simple blog:

1. HSET post:1 with fields: title → "Redis Guide", author → "Alice", views → "0"
2. SADD tag:redis with member "post:1"
3. HINCRBY post:1 views by 5
4. HGET post:1 views to see the updated view count