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Theory, Analysis
Redis Data Type

Redis Data Type

This article analyzes Redis Data Types.

1. Redis Data Type

Redis is fundamentally a storage that serves as a Key-Value Store, but it has the characteristic of supporting various Data Types for the Value.

1.1. Strings

The Strings Type is, as the name implies, a Type that stores strings. Strings can be used to store not only actual text but also various Data such as JPEG Images. When storing numbers, the INCR, DECR, and INCRBY commands can be used to change the number atomically, and when storing strings, the APPEND, GETRANGE, and SETRANGE commands can be used to manipulate the string. Bit Operations are also possible through the SETBIT and GETBIT commands. Up to 512MB can be stored.

1.2. Lists

The Lists Type is, as the name implies, a Type that stores a List of strings. The strings in the List are ordered by insertion order, and they can be added on both sides using the LPUSH and RPUSH commands, and removed from both sides using the LPOP and RPOP commands. Removing strings in the middle of the List and Sorting are not supported.

1.3. Sets

The Sets Type is similar to the Lists Type, but it does not allow duplicate values. Since it internally manages strings based on a Hash Table, it has the characteristic that string insertion and string lookup take O(1) time. Strings can be added using the SADD command and removed using the SPOP command.

1.4. Sorted sets

The Sorted sets Type is similar to the Sets Type, but differs in that it sorts by a value called Score that is stored together with the string. Therefore, when adding a string, the Score must also be set and added together. Strings and Scores can be added using the ZADD command, and the string with the largest or smallest Score can be removed using the ZPOPMIN and ZPOPMAX commands. There is no function to remove a specific string by specifying it. The ZRANGE command can also be used to get strings in a specific range based on the Score.

1.5. Hashes

The Hashes Type is a Type that stores Key-Values composed of strings. The HSET command is used to store a string Key-Value, and the HGET command is used to get the string Value through the string Key.

2. References

Recursive Algorithm Time/Space ComplexityRedis Master-slave, Cluster