1. Redis :
Redis 是一个开源的、键值对的 NoSQL 数据库。它是一种内存数据结构，用于存储从内存提供的所有数据并使用磁盘进行存储。它提供了独特的数据模型和高性能，支持各种数据结构，如字符串、列表、集合、散列，用作数据库缓存或消息代理。它也称为数据结构服务器。它不支持模式 RDBMS、SQL 或 ACID 事务。
2.内存缓存：
Memcached 是一个简单的开源内存缓存系统，可用作临时内存数据存储。存储在内存中的数据具有很高的读写性能，可以将数据分发到多个服务器中。它是存储在内存中的字符串对象的键值，该 API 可用于所有语言。 Memcached 对于网站非常有效。
Redis 和 Memcached 的区别——
| Parameter | REDIS | MEMCACHED |
|---|---|---|
| Initial Release | It was released in 2009. | It was released in 2003. |
| Developer | It was developed by Salvatore Sanfilippo. | It was developed by Danga Interactive. |
| Cores Used | It uses single cores. | It uses multiple cores. |
| Length of a key | In Redis, maximum key length is 2GB. | In Memcached, maximum key length is 250 bytes. |
| Installation | It is simple and easier to install as compared to Memcached. | It may be difficult to install. |
| Data Structure | It uses list, string, hashes, sorted sets and bitmaps as data structure. | It uses only string and integers as data structure. |
| Speed | It reads and writes speed is slower than Memcached. | It reads and writes speed is higher than Redis. |
| Replication | It supports Master-Slave Replication and Multi-Master Replication methods. | It does not support any replication method. |
| Durability | It is more durable than Memcached. | It is less durable than Redis. |
| Secondary database model | It has Document Store, Graph DBMS, Search Engine, and Time Series DBMS as secondary database models. | It has no secondary database models. |
| Persistence | It uses persistent data. | It does not use persistent data. |
| Partitioning method | It supports Sharding. | It does not support any partitioning method. |