Ch 5 · Redis Strings and Numbers · Redis
Topic 5 of 5 in Redis — Complete Tutorial (Beginner) — 4 lessons.
String Operations and Counters
Work with string operations, counters, and atomic increments. Strings are the simplest Redis type, yet they power page-view counters, like buttons and rate limits. Each command runs as one indivisible step, so two users clicking at once cannot lose a count. You will meet INCR and DECR, the batch commands MSET and MGET, and SETNX, which only sets a key that does not exist yet.
String Operations and Counters in Code
The code runs a visitor counter up to 12 using INCR twice and INCRBY once, even though the value is stored as a string. Next, MSET and MGET handle three keys in one round trip. Watch APPEND grow a message and STRLEN measure it, then see SETNX return 1 when it creates a lock key and 0 if the key already exists.
Practice: String Operations and Counters
Put strings and counters to work in three small tasks. You will count page views, store and fetch several profile fields in one go, and create a simple lock that only one process can hold. A correct answer uses clear, namespaced key names and makes sure the lock expires by itself, so a crashed program cannot leave it stuck forever.
Solution & Challenge: String Operations and Counters
Compare your work with the worked solution, which counts home-page views, saves a profile with MSET, and takes a lock using SET with NX and EX so it expires after 30 seconds. The challenge asks you to build a rate limiter that allows a set number of requests per user each minute, using INCR to count and EXPIRE to reset.