Overview and Main Concepts of Amazon DynamoDB
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DynamoDB is a NoSQL serverless database provided by AWS. It follows a key-value store structure and adopts a distributed architecture for high availability and scalability.
As in any serverless system, there’s no infrastructure provisioning needed. Dynamo offers two capacity modes that can serve both highly variable and predictable workloads.
Data is organized in tables, which contains items. Each item contains a set of key-value pairs of attributes. There are two special types of attributes: the primary-key, which works similarly to an item ID, and the sort-key, which allows for ordering the items.
Dynamo supports secondary indexes. They can be used to reference and order items by different primary-key and sort-keys. It is a schema-less database, in which items can have different sets of attributes. This allows for sparse indexes: composed only of items that contain a particular attribute.
Main Concepts of DynamoDB
Table: as a collection that can hold a virtually infinite number of items, it may also have secondary indexes associated
Secondary Index: duplicates table items using a different primary-key and sort-key
Item: the most basic unit in Dynamo, it holds the data attributes structured in a JSON
Attribute: a key value pair that contains informational data-points about an item in the database table
Primary Key: a special form of attribute that is used to reference items, similarly to an item ID
Sort Key: another special form of attribute that is used to organize items in a different sorting order
Streams: a constant stream of state-changing operations executed against a table
Query: operation to retrieve a particular item (or set of items)
Scan: oepration to scan the entire table or a section of it
Filter: rules to apply after a query or scan has executed, but before results are returned to the requester