Redis and Memcache

Redis is a NoSql DataStore
There is no need of tables structure, no insert, select statement.
Simple and straight forward data read/write.

Redis can be used with existing database to make transition faster

Redis can be used as Caching System or full fledged database

Redis can support upto 1 lac 20 thousand requests per second

Redis will be in middle and all frequently accessed data can be cached in Redis and request will not got directly to Server infact Redis will service the request

For Scaling 
Redis can be used in form of Master/ Slave relationship.

If master gores down , slave will serve the request

Redis have single text file , to store all configurations

Example

Lets suppose you wanted to access the Blog, now in blog most of the data would be static and content hardly gets change and update , in such a case we can store some amount of the data in Redis instead of hitting the database.

Redis is very fast in memory database, it provides best performance and stability 

To see the Redis keys we can use below tool (RedisDesktopManager)

 https://github.com/qishibo/AnotherRedisDesktopManager/releases

Sample Redis

Go to config and check if address is correct in config

Now open Redis Browser

Search for the keys , example : *live*

You can delete the keys using DEL Key

MemCache

MemCache will be distributed on different Servers
Hot Data from DB is stored in the cache


In this way hit rate to Database would be reduced to a very great extent.
and most of the hit would go to MemCache

Facebook is the world's heaviest memcached user  20+ terabytes of RAM ,800+ Servers
Simple Commands
get key, set key, delete key