What data is stored in the redis cache?

String string:

The string type is the most basic data storage type in Redis, which is composed of bytes The sequence is binary safe in Redis, which means that this type can accept data in any format, such as JPEG image data or Json object description information, etc. is a standard key-value, generally used to store characters. Strings, integers and floating point numbers. The maximum data length that Value can hold is 512MB (Recommended learning: Redis Video Tutorial)

Application scenario: A very common scenario is used to count the number of website visits, the number of people currently online, etc. incr command (operation)

List list:

Redis' list allows the user to push or pop elements from both ends of the sequence. The list consists of multiple characters An ordered and repeatable sequence composed of string values ​​is a linked list structure, so the time complexity of adding elements to both ends of the list is 0(1). The closer to the two ends of the list, the faster it is to obtain the elements.

This means that even for a list with tens of millions of elements, getting the 10 records at the head or tail is extremely fast. The maximum number of elements that can be contained in a List is 4294967295.

Application scenarios: 1. Latest news rankings. 2. Message queue to complete message exchange between multiple programs. You can use the push operation to store the task in the list (producer), and then the thread uses the pop operation to take the task out for execution. (Consumer)

Hash hash:

The hash in Redis can be regarded as a map container with String key and String value, and multiple Key-values ​​are stored in a key. Each Hash can store 4294967295 key-value pairs.

Application scenarios: such as storing, reading, and modifying user attributes (name, age, pwd, etc.)

Set:

Redis collections are unordered and non-repeatable. Like lists, they are very efficient when performing insertion and deletion and determining whether an element exists. The biggest advantage of sets is that they can perform intersection, union, and difference operations. The maximum number of elements that a Set can contain is 4294967295.

zset (sorted set: ordered set)

Redis zset, like set, is also a collection of string type elements, and duplicate members are not allowed.

The difference is that each element is associated with a double type score. Redis uses scores to sort the members of the collection from small to large.

The members of zset are unique, but the scores can be repeated.

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