Lesson 9 / 18

Hashes

A field-value map inside one key — like a mini object.

HSET & HGET

A hash groups related fields under one key instead of spreading them across many SET calls.

HSET user:1 name "Ada" age "36" city "London"
HGET user:1 name
HGETALL user:1

Output:

(integer) 3
"Ada"
1) "name"
2) "Ada"
3) "age"
4) "36"
5) "city"
6) "London"

Updating one field

HINCRBY bumps a numeric field without touching the rest of the hash.

HINCRBY user:1 login_count 1

Output:

(integer) 1

A record in a drawer

Think of a hash as one drawer (user:1) holding labeled slips of paper (fields) — you can pull out just name without opening the whole drawer.