The difference between Redis and memcache

The difference between Redis and memcache

Summary one:

1. Data type

Redis data type rich, support set Liset and other types
Memcache supports simple data types and requires clients to handle complex objects themselves

2. Persistence

Redis supports data-on-ground persistent storage
Memcache does not support data persistent storage

3. Distributed storage

Redis supports Master-slave replication mode
Memcache can be distributed using consistent hash

Value varies in size

Memcache is a memory cache, the key is less than 250 characters in length, and a single item store is less than 1M, not suitable for use by a virtual machine

4. Data consistency is different

Redis uses a single-threaded model to ensure that the data is submitted sequentially.
Memcache need to use CAS to ensure data consistency. CAS (Check and Set) is a mechanism for ensuring concurrency consistency and belongs to the "optimistic lock" category; The principle is simple: take the version number, the operation, the comparison version number, if the same operation, inconsistent to abandon any operation

5.CPU Utilization

The Redis single-threaded model can use only one CPU to open multiple Redis processes

Summary two:

1.Redis, not all of the data has been stored in memory, which is the biggest difference compared with memcached.
2.Redis not only supports simple k/v types of data, but also provides storage of data structures such as List,set,hash.
3.Redis backup of supporting data, i.e. Master-slave mode data backup.
4.Redis support data persistence, you can keep the in-memory data on the disk, restart the time can be loaded again for use.
I personally think that the most fundamental difference is that Redis has a database feature in many ways, or a database system, and memcached is simply a k/v cache

Summary three:

The difference between Redis and Memecache is that:

1. Storage mode:
Memecache all of the data in memory, will be suspended after the power outage, the data can not exceed the memory size
Redis is partially present on the hard drive, which guarantees the data's durability.
2. Data support type:
Redis has much more data support than Memecache.
3, using the underlying model is different:
The new version of Redis directly builds its own VM mechanism, because a system function called by a general system can waste a certain amount of time moving and requesting.
4, the operating environment is different:
Redis currently only supports Linux, eliminating the support for other systems, which can be used to better optimize the environment of the system, although Microsoft has a team to write a patch for it. But not on the trunk.

Memcache can only be cached, cache
Redis content can be landed, which is similar to MongoDB, then Redis can also be used as a cache, and can be set Master-slave

The difference between Redis and memcache