面试题与答案

Replication is important in order to archive high level of availability in big data systems. The data needs to be replicated at n number of places. This follows the master-slave approach where the master copy is maintained by master-slave and replicated to n other nodes.

Following is a list of some important advantages of Redis:

• Redis is very fast.
• It supports a server-side locking.
• It has a rich client side library.
• It is a good counter.
• It supports Atomic Operation.

Following are the disadvantages/ limitations of Redis:

• It is single threaded.
• It has got limited client support for consistent hashing.
• It has significant overhead for persistence.
• It is not deployed widely.

There are a lot of differences between Redis and RDBMS:

• Redis is a NoSQL database while RDBMS is an SQL database.
• Redis follows the key-value structure while RDBMS follows the table structure.
• Redis extremely fast while RDBMS is comparatively slow.
• Redis stores all the dataset in primary memory while RDBMS stores its dataset in secondary memory.
• Redis is generally used to store small and frequently used files while RDBMS is used to store big files.
• Redis provides only official support for Linux, BSD, Mac OS X, Solaris. It doesn?t provide official support for Windows currently while RDBMS provides support for both.