A list preserves the order of elements and supports access by index. This makes it suitable for tasks such as creating task queues, logging events, or storing real-time data like recent user activities.

The Main Commands for Working With Lists in Redis

The key commands for working with lists in Redis include several categories, each addressing a specific task: adding, retrieving, reading, modifying, deleting elements, and managing the list's size.

Adding Elements to a List

Redis provides two commands for adding elements to a list: LPUSH and RPUSH, which add elements to the beginning and the end of the list, respectively.

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LPUSH tasks "Task1" "Task2"  # adds to the beginning
RPUSH tasks "Task3" "Task4"  # adds to the end

After executing these commands, the tasks list will look like this: ["Task2", "Task1", "Task3", "Task4"].

Removing Elements from a List

To remove elements from a list, Redis provides two commands: LPOP and RPOP, which remove and return elements from the beginning and the end of the list, respectively.

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LPOP tasks  # removes and returns "Task2"
RPOP tasks  # removes and returns "Task4"

After executing these commands, the tasks list will look like this: ["Task1", "Task3"].

Reading Elements from a List

To read elements from a list, Redis offers the commands LRANGE, LINDEX, and LLEN. LRANGE and LINDEX allow you to retrieve elements by index, while LLEN returns the total number of elements in the list.

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LRANGE tasks 0 -1  # returns all elements in the list
LINDEX tasks 0    # returns the first element
LLEN tasks        # returns the length of the list

• LRANGE will return all elements: ["Task1", "Task3"];

• LINDEX will return "Task1";

• LLEN will return 2.

Modifying a List

To modify an element in a list, use the LSET command, which allows you to update an element at a specific index.

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LSET tasks 1 "UpdatedTask"  # updates the second element to "UpdatedTask"

After executing this command, the tasks list will be: ["Task1", "UpdatedTask"].

Trimming a List

The LTRIM command is used to trim a list, keeping only the elements within a specified range. All other elements will be removed.

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LTRIM tasks 0 1  # keeps only the first two elements

If the tasks list was: ["Task1", "Task2", "Task3"], after executing the command, the list will contain: ["Task1", "Task2"].