Are there big differences between the five data types of redis?

Redis provides five basic data types: string (unstructured binary string), hash (key-value pair collection), list (ordered element sequence), set (unduplicate element collection), Sorted set (a set of ordered elements with fractions). They differ in data structure, operations, memory efficiency, and application scenarios, making them suitable for different use cases.

Differences between Redis’s five data types

Redis provides five basic data types, each type has Different features and use cases. The differences between these data types are mainly reflected in the following aspects:

1. Data structure

• String (String): Unstructured binary safe string.
• Hash: A collection of key-value pairs of fields and values.
• List (List): An ordered sequence of elements, supporting double-ended insertion and deletion.
• Set: An unordered collection of non-repeating elements.
• Ordered Set (Sorted Set): An ordered set of elements with scores, supporting sorting by score.

2. Operation

Different data types support different sets of operations, for example:

• String: concatenation, Interception, append, etc.
• Hash: set/get fields, get field counts, etc.
• List: insert/delete elements, get element index, etc.
• Collection: add/delete Elements, finding members, etc.
• Ordered collections: adding/removing elements, finding elements by score, etc.

3. Memory efficiency

Each data type also differs in memory usage:

• String: stores the actual data, memory usage is proportional to the data length.
• Hash: Use a hash table to store key-value pairs, keys and values ​​share memory, and memory usage is small.
• List: Elements are stored in contiguous memory blocks, and memory usage is proportional to the number of elements.
• Collections: Elements are stored in a hash table, and memory usage is proportional to the number of elements.
• Ordered set: elements are stored in jump lists, and memory usage is related to the number of elements and score distribution.

4. Application scenarios

According to different characteristics, each data type is suitable for different application scenarios:

• Characters String: stores simple data, such as configuration information, cache content, etc.
• Hash: stores key-value pair information, such as user data, metadata, etc.
• List: Stores an ordered sequence of elements, such as message queue, timeline, etc.
• Collection: stores unique elements, such as tags, visited items, etc.
• Ordered collection: stores elements with scores, such as rankings, priority queues, etc.

To sum up, the five data types of Redis are different in terms of data structure, operation, memory efficiency and application scenarios. Understanding these differences is critical to choosing the right type to optimize application performance.

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