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Throughput and Pricing Example 1 (from Amazon docs)

Your application needs to perform 5 million writes and 5 million eventually consistent reads per day on a DynamoDB table, while storing 8 GB of data. Items are no larger than 1 KB in size. 

Pricing: $0.47 per WCU per month, At $0.09 per RCU per month, $0.25 per GB per month.

Write Capacity Units (WCUs)

= 5 million writes per day

= 57.9 writes per second.

1 WCU can handle 1 write per second, so you need 58 WCUs.

At $0.47 per WCU per month, 58 WCUs costs $27.26 per month.

DynamoDB throughput provisioning might look bit difficult to understand and hence adding examples.

Throughput Provisioning - Basic Concepts

Provisioned Throughput (Write)

• One write capacity unit (WCU) provides up to one write per second

• Enough for 2.5 million writes per month               

• Price as low as  $0.47 per WCU

Pay only for the resources you provision.

You do not allocate memory, CPU, and other system resources. Instead you specify the target utilization rate and minimum to maximum capacity that you want for your table.

DynamoDB handles the provisioning of resources to achieve your target utilization of read and write capacity, and also auto scales your capacity based on usage. 

Optionally, you can directly specify read and write capacity if you prefer to manually manage table throughput.

Updating items in DynamoDB has two special cases - Conditional Operations and Atomic Counters.  

Conditional Operations and Expressions

By default, the DynamoDB write operations (PutItem, UpdateItem, DeleteItem) are unconditional: each of these operations will overwrite an existing item that has the specified primary key. In certain cases such as multiple users attempting to modify the same item, this might create problems.

Will discuss the basic DynamoDB operations such as create table, and CRUD operations such as insert, read, update and delete.

Creating Table

Can create table using Management Console or CreateTable API.

Insert Data

Can use the PutItem or BatchWriteItem APIs.

PutItem API is idempotent.

DynamoDB primary key fields are called Partition Key and Sort Key. DynamoDB also support two types of secondary indexes, that allows to query on any attribute (column) other that primary key:  Global Secondary Indexes (GSI) and Local Secondary Indexes (LSI).

Data model for DynamoDB comprises of tables, items (rows) and attributes.

Table

A table is a collection of data items.

Table can have a single primary key called partition key or a composite key which contains both partition key and sort key.

Item (row)

An item is synonymous to a row in a traditional database.

1. DynamoDB is integrated with Elasticsearch using the Amazon DynamoDB Logstash Plugin.

   1. With this integration, you can easily search DynamoDB content such as messages, locations, tags, and keywords.

DynamoDB is a fully managed distributed NoSQL database service from Amazon and as per Amazon, it can scale without limits.

 DynamoDB is the most popular NoSQL cloud database according to Forrester, as of Jan 2017.

DynamoDB automatically partitions and re-partitions your data as your table size grows.

An Amazon Machine Image (AMI) provides the information required to launch an EC2 instance.  

You specify an AMI when you launch an instance, and you can launch as many instances from the AMI as you need.

You can also launch instances from as many different AMIs as you need.

An AMI includes the following:

1. A template for the root volume for the instance (for example, an operating system, an application server, and applications)