AWS : Dynamo DB : Developer : Section 22

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NoSQL serverless

DynamoDB Is serverless database . it is managed by AWS and it will scale for you. It is well integrated with AWS lamda and other AWS services . We will learn

how do design a dynamo db table
How to enable streams and how to ensure your Dynamodb table is fully secured

But if you add read replicas you are going to be limited to how many read replicas you can have .

How to choose a Primary key for Dynamo DB

You have two options for primary Key .

317. DynamoDB Basics Hands On

We start by creating a Table not a Database in a normal scenario

It is Create a Table Not Create Database .

Thats because the database is already created , so the only constraint you have is to create a Dynamo DB. so there is no provisioning of a database or so on and that makes it a server-less offering .

Table_Name : Users and then we have an option to choose Partition key and optionally a sort key

Here we have setting for the table . Here we have default table and customized settings .

With default setting we get the following

We chose to take customized settings .

we are going to disable auto scaling and we are going to provision two

disable auto scaling for write capacity

Hit create table

Click on the User Table

click on View Items

click create an Item

We need to define the partition Key for example .

You can create attributes by clicking attributes

This can be used via a form or a JSON document

Create a Second Item

If I create the same user id as before I will have a problem

Something very interesting will happen .

In RDBMS database it will mention that the coloumns are missing but in here you can have just the what ever is possible

In Dynamo DB it is completely fine to add attributes over time. Dynamo DB is done at the region level.

318. DynamoDB WCU & RCU - Throughput

Exponential is the process of retrying your read / write when you receive Provisioned Throughtput Exceeded Exception and now you will have to retry the read / write this is called Exponential Backoff.

Write Capacity Units are easy to understand . The complicated ones are read capacity .

There are two kinds of read mode for DynamoDB

Lets see how Dynamo DB works in the backend with partitions .

Partions copies of data that living on specific servers

When the application writes into the Dynamo DB it send some partitions key , some sort key perhaps too to the dynamo db database and all these data is going to go through an Hashing Algorithm to understand which partition to go to .

If you take the example of the below diagram and take the partition key of 13