Dynamo DB

DynamoDB: 

• DynamoDB is a fast and flexible NoSQL database service for all applications that need consistent, single digit millisecond latency at any scale. It is a fully managed database and supports both document and key-value data models. Its flexible data model and reliable performance make it a great fit for mobile, web, gaming, ad-Tech, IoT and many other applications.
• Stored on SSD storage.
• Spread across three geographically distinct data centers.
• If any data is written to one of the table in DynamoDB, the data is then written to other two locations. There are two different data consistency models:

1. Eventual Consistent Reads(Default):
   Consistency across all copies of data is usually reached within a second. Repeating a read after a short period of time should return the updated data.(Best read performance).
2. Strongly Consistent Reads:
   A strongly consistent read returns a result that reflects all writes that received a successful response prior to the read.

The Basics of DynamoDB:

• Tables
• Items(Think a row of data in a table)
• Attributes(Think of a column of data in a table).
• DynamoDB allows nested attributes upto a level of 35.
  

Pricing :

• Provisioned throughput capacity:
  
  • write throughput of 0.0065$ /hr/10 units.
  • read throughput of 0.0065$ /hr/50 units.
  • Storage cost is 0.25$ per GB per month.
  
  First 25GB stored/month is free.
  After that 0.25GB/GB/Month.
  
  
• For Ex:- Our application needs 1M reads and writes per day. Dividing 1M (1,000,000)
  -- 1,000,000/(24 hrs)/60(Mins)/60 Secs -> 11.6 reads per second
  Dynamo DB can handle 1 write capacity per second, so we ll need 12 write capacities through out the day
  Per Unit write is 0.00065$ -- so per day will cost --> 0.00065$*12*24 hrs = 0.1872 per day
  Per Unit read is 0.0065/50 --> so per day will cost --> 0.0065/50*12*24 = 0.0374
• If the total storage for out application is 30GB, since 25GB is free, we have to pay for the extra 5GB which is 0.25*5 = 1.25$ per month.
• The total is 1.25$ + (0.1872$+0.0374$)*30.