zset

zset, also known as a sorted set, is a data structure that stores a collection of elements, where each element is associated with a score. The elements within a zset are unique, but their scores can be duplicated. The primary characteristic of a zset is that its elements are ordered based on their scores, typically in ascending order. This ordering allows for efficient retrieval of elements within a given score range or retrieval of the elements with the highest or lowest scores.

Operations commonly supported by zsets include adding new elements with their scores, updating the score of an existing element, removing elements, and querying elements by their rank (position in the sorted order) or by a score range. These operations are generally performed with logarithmic time complexity relative to the number of elements in the set. Zsets are useful in scenarios where maintaining an ordered collection based on a numerical value is important, such as leaderboards in games, ranking systems, or implementing priority queues. Many in-memory data stores, like Redis, provide robust implementations of sorted sets.