Five commonly used data types in redis
1. String string:
characters The string type is the most basic data storage type in Redis. It is a sequence composed of bytes. It is binary safe in Redis, which means that this type can accept data in any format, such as JPEG image data or Json objects. Description information, etc., are standard key-values, generally used to store strings, integers and floating point numbers. The maximum data length that Value can hold is 512MB
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)
2. List list:
Redis' list allows users to push or pop elements from both ends of the sequence. The list consists of multiple strings An ordered and repeatable sequence of values is a linked list structure, so the time complexity of adding elements to both ends of the list is 0(1), and the closer to the two ends of the list, the faster it is to obtain 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)
3. Hash hash:
The hash in Redis can be regarded as a map container with String key and String value, and multiple Key-value is stored in a key. Each Hash can store 4294967295 key-value pairs.
Application scenarios: such as storing, reading, modifying user attributes (name, age, pwd, etc.)
4. Collection set:
Redis The set is unordered and non-repeatable. Like the list, it is 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.
Application scenarios: 1. Use intersection to find common friends. 2. Using uniqueness, all independent IPs that visit the website can be counted. 3. When friends recommend, the intersection is found based on the tag. If it is greater than a certain threshold (critical value), the recommendation can be made.
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