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Day 1 of 5
⏱ ~60 minutes
Redis in 5 Days — Day 1

Redis Data Types

Install Redis, use redis-cli, and work with all five core data types.

Redis Is Not a Cache. It's a Data Structure Server.

Most developers think of Redis as a cache. It is one, but it's also much more. Redis keeps all data in memory (fast) and persists to disk (durable). It has five data structures that solve specific problems elegantly.

Install and connect
# Mac: brew install redis
# Linux: sudo apt install redis
redis-server &
redis-cli
Strings
SET name 'Alice'
GET name

SET counter 0
INCR counter         # atomic increment → 1
INCRBY counter 5     # → 6
DECR counter         # → 5

SET token 'abc123' EX 3600   # expires in 1 hour
TTL token                     # time remaining (seconds)
PERSIST token                 # remove expiration
Hashes (like a row in a table)
HSET user:1 name Alice email [email protected] age 28
HGET user:1 name
HGETALL user:1
HMSET user:2 name Bob email [email protected]
HDEL user:1 age
HEXISTS user:1 email
Lists, Sets, Sorted Sets
# Lists (ordered, allows duplicates)
LPUSH mylist 'a' 'b' 'c'    # push to head
RPUSH mylist 'd'             # push to tail
LRANGE mylist 0 -1           # get all
LPOP mylist                  # pop from head

# Sets (unordered, unique members)
SADD tags python javascript rust
SMEMBERS tags
SISMEMBER tags python        # 1 if member
SCARD tags                   # count

# Sorted Sets (score + member)
ZADD leaderboard 100 alice 85 bob 92 carol
ZRANGE leaderboard 0 -1 WITHSCORES
ZRANK leaderboard alice      # 0-based rank
ZREVRANK leaderboard alice   # rank from top
📝 Day 1 Exercise
Build a Leaderboard
  1. U
  2. s
  3. e
  5. a
  7. s
  8. o
  9. r
  10. t
  11. e
  12. d
  14. s
  15. e
  16. t
  18. t
  19. o
  21. b
  22. u
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  24. l
  25. d
  27. a
  29. g
  30. a
  31. m
  32. e
  34. l
  35. e
  36. a
  37. d
  38. e
  39. r
  40. b
  41. o
  42. a
  43. r
  44. d
  45. .
  47. A
  48. d
  49. d
  51. 1
  52. 0
  54. p
  55. l
  56. a
  57. y
  58. e
  59. r
  60. s
  62. w
  63. i
  64. t
  65. h
  67. s
  68. c
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  70. r
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  75. F
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  78. c
  79. h
  81. t
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  83. e
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  87. p
  89. 3
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  92. U
  93. p
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  95. a
  96. t
  97. e
  99. a
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  102. l
  103. a
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  105. e
  106. r
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  112. o
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  117. G
  118. e
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  121. t
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  127. n
  128. k
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  146. a
  147. y
  148. e
  149. r
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  152. S
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  159. a
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  161. h
  163. p
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  165. a
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  167. e
  168. r
  169. '
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  175. f
  176. i
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  178. e
  180. i
  181. n
  183. a
  185. h
  186. a
  187. s
  188. h
  189. .

Day 1 Summary

  • Strings: SET/GET/INCR/TTL. Set expiration with EX. Good for simple values, counters, tokens.
  • Hashes: store object fields. HSET/HGET/HGETALL. One key, many fields.
  • Lists: ordered, allows duplicates. LPUSH/RPUSH/LRANGE. Good for queues and timelines.
  • Sorted Sets: members with scores. ZADD/ZRANGE/ZRANK. Perfect for leaderboards and rate limiting.
Next →
Day 2: Caching Patterns
→
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