Understanding Redis Commands and Its Five Data Types

Redis Commands

Redis commands are used to perform specific operations on a Redis server.

Example on Linux:

cd /tools/redis-7.0.5/bin
./redis-cli

To connect to a remote server: redis-cli -h host -p port -a password Replace host with the IP address, port with the port number, and password with the appropriate password.

Redis Five Data Types

String – The most common type for simple values. Common commands:

set key value – set the value of a key

get key – retrieve the value of a key

getrange key start end – get a substring of the value

setex key seconds value – set the value and its expiration time (seconds)

setnx key value – set the value only if the key does not already exist

List – An ordered collection of strings, sorted by insertion order.

Set – A collection of unique string members; duplicate elements are not allowed.

Sorted Set – Similar to a Set but each member is associated with a double‑precision score that determines the ordering from low to high.

Hash – A map of string fields to string values, ideal for representing objects. A single hash can store roughly 4 billion field‑value pairs. Common commands:

HDEL key field1 [field2] – delete one or more fields from the hash

HEXISTS key field – test whether a field exists in the hash

HGET key field – retrieve the value of a specific field

These are the commands we use most frequently; many other commands exist but are omitted here.

We will continue to use these five data types in future articles, such as detailed explanations of implementing likes and unlikes with Redis.