Amazon DynamoDB differs from traditional relational databases in several key ways:
Data Model :
* DynamoDB uses a key-value and document-based data model, whereas traditional relational databases use a tabular data model with rows and columns.
* DynamoDB allows flexible schema design, where each item (equivalent to a row in RDBMS) can have different attributes, whereas RDBMS requires a fixed schema with predefined tables and columns.
Scalability and Performance :
* DynamoDB is designed for horizontal scalability and can handle large volumes of data and high throughput by distributing data across multiple servers. It can automatically scale up or down based on demand. Traditional relational databases may have limitations in scaling horizontally, often requiring manual sharding or partitioning.
* DynamoDB offers single-digit millisecond latency for read and write operations, making it suitable for real-time applications that require low-latency responses. Traditional relational databases may struggle to achieve such performance at scale.
Consistency Model :
* DynamoDB offers eventual consistency or strong consistency, depending on the read operations. It follows an eventually consistent model by default but allows users to request strongly consistent reads when needed. Traditional relational databases typically provide strong consistency by default.
Transactions :
* DynamoDB supports ACID transactions within individual items, allowing multiple write operations within the same item to be atomic, consistent, isolated, and durable. However, it does not support multi-item transactions spanning multiple items or tables. Traditional relational databases often provide support for complex transactions involving multiple rows or tables.
Indexes :
* DynamoDB supports global and local secondary indexes, which allow querying table data using non-primary key attributes. Traditional relational databases offer various types of indexes (e.g., B-tree, hash) to optimize query performance.
Data Integrity and Referential Integrity :
* DynamoDB does not enforce referential integrity constraints or foreign key relationships between tables. It is up to the application to maintain data integrity. Traditional relational databases enforce referential integrity constraints, ensuring data consistency and preventing orphaned records.
Cost Model :
* DynamoDB offers a pay-per-use pricing model, where customers pay for the resources (storage, throughput capacity) they consume. Traditional relational databases may have licensing fees and upfront costs, along with additional expenses for hardware, maintenance, and administration.
