Database

Collections -> Similar to table

Documents -> Similar to rows -> Docs in docs are allowed

BSON -> Binary JSON -> To make server more quick

MongoDB Atlas

                       Availability

MySql Casandra

Consistency Partition-Tolerance

               Apache HBASE   mongoDB

Replication Set

Single Master

Maintains backup copies of your database instances

Majority servers in your set must agree on the primary

Repilca set address durability not for scaling.

https://www.youtube.com/watch?v=UFVFIKduXpo

Sharding

For Scaling

Ranges of some indexed value you specify are assigned to different replica sets

Issues with Auto Sharding

It sometimes doesn't work -> Split storms, mongos restarted too often

You must have 3 config servers

loose doc model can be at odds with effective sharding

GridFS