面试题与答案

DynamoDB supports two types of primary keys: partition key and composite key (partition key + sort key).

Provisioned Throughput is the capacity (read and write) reserved for a table. It ensures predictable performance.

DynamoDB is a NoSQL database with a flexible schema, automatic scaling, and high availability, while traditional relational databases are SQL-based with a fixed schema.

DynamoDB achieves scalability and high availability through partitioning, replication, and automatic sharding of data across multiple servers.

Consistent Read ensures that a read operation returns the most up-to-date data reflecting all writes that are acknowledged before the read.

A Local Secondary Index is an index that has the same partition key as the base table but a different sort key. It allows efficient querying of data within a single partition.

An Item Collection is a set of items that have the same partition key value in a table with a composite primary key. Collections are formed when a table has a sort key.

DynamoDB uses conditional writes and optimistic concurrency control to handle conflicts in write operations. Conditional writes allow you to specify conditions for write operations to succeed.

TTL is a feature in DynamoDB that allows you to automatically expire items from a table after a specified time. It is useful for managing data that has a limited lifespan.

DynamoDB Streams capture changes to items in a table, including new items, updates, and deletions. It allows you to process and react to changes in real-time.

DynamoDB is schema-less, allowing you to add or remove attributes at any time without affecting existing items. Indexes need to be created or modified separately.

The 'Scan' operation in DynamoDB reads every item in a table, making it less efficient than 'Query.' It should be used sparingly and is often used when a table has no defined schema.

DynamoDB provides both eventual and strong consistency. By default, read operations are eventually consistent, but you can request strongly consistent reads when needed.

'BatchGetItem' retrieves multiple items from one or more tables using their primary keys. It allows efficient retrieval of multiple items in a single request.

'UpdateItem' modifies existing attributes or adds new ones to an existing item, while 'PutItem' creates a new item or replaces an existing item with a new one.

The 'Query' operation retrieves items from a table using a specified primary key or index key. It is more efficient than 'Scan' for retrieving a subset of items.

Conditional Writes allow you to specify conditions that must be satisfied for a write operation to succeed. It helps in avoiding conflicts and ensuring data integrity.

DynamoDB uses AWS Identity and Access Management (IAM) to control access to tables. You can define fine-grained access policies to control who can perform specific actions.

'BatchWriteItem' writes multiple items to one or more tables using a single request. It is more efficient than making individual 'PutItem' or 'DeleteItem' calls.

PITR allows you to restore a table to any point in time within the last 35 days. It helps in recovering from accidental data loss or corruption.

DynamoDB encrypts data at rest using AWS Key Management Service (KMS) and supports encrypted connections (SSL/TLS) for data in transit.

'UpdateTable' is used to modify the provisioned throughput settings for a table. It can be used to increase or decrease the capacity of a table.

DynamoDB supports on-demand backups and enables Point-in-Time Recovery (PITR). Backups can be used to restore a table to any point in time within the last 35 days.

'BatchGetItem' retrieves multiple items from one or more tables using their primary keys. It allows efficient retrieval of multiple items in a single request.