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03-REDIS-STRINGS.md

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Strings

Strings are the simplest data structure in Redis. They're called Strings but they're really more insteresting and can contain numbers and binary data as well as text.

Use GET and SET to, well, get and set a String in Redis. Quotes are optional but needed if you have any whitespace in your string. You can use either single- or double-quotes, just like in JavaScript. Escape quotes within your string with a backslash, also just like in JavaScript.

Try getting and setting the message of the day for our Bigfoot Tracker:

127.0.0.1:6379> SET motd Greetings!
OK
127.0.0.1:6379> GET motd
"Greetings!"

📍 Figure It Out

  • What happens when you get a String that isn't there?
  • Try changing the message of the day to a message with whitespace. Try one with quotes.
  • How do you think you might set a String with a tab or a new-line?

String Containing Integers

String in Redis can be numbers. Weird, I know, but try it:

127.0.0.1:6379> SET sightings:count 42
OK
127.0.0.1:6379> GET sightings:count
"42"

I know what you're thinking—that's just a String containing a number. But it's not. Redis stores this internally as a 64-bit signed integer. This let's you modifiy it numerically using a handful of commands.

Use INCR and DECR to increment and decrement a String:

127.0.0.1:6379> INCR sightings:count
(integer) 43
127.0.0.1:6379> GET sightings:count
"43"

Next, use INCRBY and DECRBY to increment and decrement by a specified amount:

127.0.0.1:6379> DECRBY sightings:count 20
(integer) 23
127.0.0.1:6379> GET sightings:count
"23"

📍 Figure It Out

  • What happens when you increment or decrement a String that isn't there?
  • What about a String that doesn't contain a number?
  • What happens when you give INCRBY and DECRBY negative numbers?

Before we explore the next data structure, let's learn some of the commands for manipulating keys in Redis.