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SORT

Sorts the elements of a list, set, or sorted set in a Redis database.

Syntax​

SORT key [BY pattern] [LIMIT offset count] [GET pattern [GET pattern ...]] [ASC|DESC] [ALPHA] [STORE destination]

Parameters​

  • key: The key of the list, set, or sorted set to be sorted.
  • BY pattern (optional): A pattern to sort the elements by the values of another key. This is used with LIST or SET data types.
  • LIMIT offset count (optional): Limits the number of elements returned. offset is the starting index, and count is the maximum number of elements to return.
  • GET pattern [GET pattern ...] (optional): Retrieves specific fields for each element. Multiple GET patterns can be used to fetch different fields.
  • ASC|DESC (optional): Specifies the sort order. Use ASC for ascending order and DESC for descending order. Default is ASC.
  • ALPHA (optional): Sorts elements as strings. By default, sorting is numerical if the elements are numbers.
  • STORE destination (optional): Stores the sorted elements into a new key. This is useful for persisting the result.

Details​

  • Available since: 1.0.0
  • Time complexity: O(N*log(N)), where N is the number of elements to sort.
  • ACL categories: @read, @write

The SORT command is used to sort the elements of a list, set, or sorted set in Redis. The sorting can be based on the values of the elements or another key, and it supports various options for filtering and storing results.

Examples​

Sorting a List​

To sort a list in ascending order:

SORT mylist

Assuming mylist contains numerical values, this command will return the list sorted in ascending order.

Sorting with Pattern​

To sort elements based on another key:

SORT myset BY myotherkey:*

Here, myset is sorted based on the values associated with myotherkey.

Sorting with Limit​

To sort and limit the results:

SORT mylist LIMIT 0 10

This command sorts mylist and returns only the first 10 elements.

Sorting with Field Retrieval​

To sort and get specific fields:

SORT mylist GET mylist:* GET mylist:field2

This sorts mylist and retrieves two fields for each element: mylist:* and mylist:field2.

Sorting and Storing Results​

To sort and store results in a new key:

SORT mylist STORE sortedlist

This command sorts mylist and stores the result in sortedlist.

RESP2/RESP3 Reply​

  • Array reply: The sorted elements or an array of elements based on the specified options.

Example Reply​

For SORT mylist, if the list contains [3, 1, 2], the reply will be:

1) "1"
2) "2"
3) "3"

For sorting with GET, the reply will include the fetched fields.

Notes​

  • The SORT command is powerful but can be expensive in terms of performance for large datasets. Use it judiciously in high-performance applications.
  • The command operates on lists, sets, and sorted sets differently. Ensure that the key you are sorting is of the correct type.
  • When using STORE, ensure the destination key does not already exist, as it will be overwritten.