- Binary-safe strings.
- Lists: collections of string elements sorted according to the order of insertion. They are basically linked lists.
- Sets: collections of unique, unsorted string elements.
- Sorted sets, similar to Sets but where every string element is associated to a floating number value, called score. The elements are always taken sorted by their score, so unlike Sets it is possible to retrieve a range of elements (for example you may ask: give me the top 10, or the bottom 10).
- Hashes, which are maps composed of fields associated with values. Both the field and the value are strings. This is very similar to Ruby or Python hashes.
- Bit arrays (or simply bitmaps): it is possible, using special commands, to handle String values like an arrayof bits: you can set and clear individual bits, count all the bits set to 1, find the first set or unset bit, and so forth.
- HyperLogLogs: this is a probabilistic data structure which is used in order to estimate the cardinality of a set. Don't be scared, it is simpler than it seems... See later in the HyperLogLog section of this tutorial.
找相应的命令请翻手册: commands, 简单可以分为以下几种:
- sorted sets
- Lists: Lists are useful for a number of tasks,
- Remember the latest updates posted by users into a social network.
- Communication between processes, using a consumer-producer pattern.
- Sets: tags
- Sorted sets: rank