Redis All

Questions:
What is Redis?Why use Redis?
Redis vs Hashmap?
Db in Redis?
Common commands:
  How to get all keys in Redis?
  How to delete all keys?
  How to set expiry time?

If redis is single threaded how can it efficiently serve so much requests?( ------ uses event loop,)
What is NoSQL? Types, popular, use cases?
Redis vs MongoDB?  
How to use Redis from Java?
Transactions in redis? multi vs pipelining?
SharedHashMap vs Redis
Memcached vs Redis
If redis is single threaded, why jedis pool( to make it responsive?)
What is jedis?


ANSWERS

What is Redis? Why use it?
Redis(Remote Dictionary Server) is a NoSQL, key-value database. It is open-source,networked, in-memory, and stores keys with optional durability.
Using Redis has a lot of benefits:
1) Redis supports clustering. This will help in making app scalable.
3) Redis supports ttl.
4) Redis does persistence on hard disk too, so safe from failure.
5) Access over command line
-Supports a lot of languages
-Supports not only strings but many abstract data types like list,set,etc.
-Supports transactions(optimistic-locking) (?)
-Pub-sub

Redis vs Hashmap?
Redis vs Hashmap:
1) Redis supports clustering. This will help in making app scalable.
2) Redis doesn't has garbage collector, while hashmap will gradually become slow due to gc.
3) Redis supports ttl.
4) Redis does persistence on hard disk too, so safe from failure.
5) Access over command line

Db in Redis?

Common commands:
  How to get all keys in Redis?: keys *
  How to delete all keys? flushdb, flushall
  How to set expiry time?

If redis is single threaded how can it efficiently serve so much requests?( ------ uses event loop)

What is NoSQL? Types, popular, use cases?

Redis vs MongoDB?
 
How to use Redis from Java?

Transactions in redis? multi vs pipelining?

SharedHashMap vs Redis

Memcached vs Redis

If redis is single threaded, why jedis pool( to make it responsive?)

What is jedis?