面试题与答案

A Global Secondary Index allows querying a table based on alternate keys in addition to the primary key. It provides more flexibility in querying data.

On-Demand Throughput allows you to pay per request without capacity planning, while Provisioned Throughput requires capacity planning and offers cost savings for consistent workloads.

Best practices include choosing the right primary key, using appropriate read and write capacities, avoiding hot keys, and utilizing secondary indexes judiciously.

DAX is an in-memory caching service that provides fast read access to frequently accessed data in DynamoDB, reducing the need to read from the DynamoDB table directly.

Provisioned Concurrency is a feature that ensures that a specified number of read and write capacity units are always available for your table, reducing warm-up times.

Auto Scaling automatically adjusts the provisioned read and write capacity based on the actual usage of a table. It helps in handling varying workloads.

Limitations include a maximum item size of 400 KB, a maximum of 256 tables per region per account, and a maximum provisioned capacity of 40,000 read and write capacity units.

DynamoDB is a NoSQL database service, while Amazon RDS is a relational database service. DynamoDB is designed for scalability and high availability, while RDS offers traditional relational database features.

'TransactWriteItems' allows you to perform multiple write operations as a single, atomic transaction. Either all the operations in the transaction succeed, or none of them are applied.

DAX provides low-latency read access to DynamoDB tables by caching frequently accessed data. It reduces the need to read from the DynamoDB table directly, improving application performance.

DynamoDB supports transactions using the 'TransactWriteItems' operation. It allows you to group multiple write operations into a single, atomic transaction.