AWS DynamoDB Interview questions, this session of the blog covers AWS DynamoDB, an Amazon Web Services (AWS) NoSQL database service offering fast and predictable performance with seamless scalability, making it suitable for data storage and retrieval from anywhere across the web.

AWS DynamoDB was specifically created for mission-critical applications with multiple failover sites for high availability, fault tolerance, and distributed storage capabilities.

We will explore some of the more frequently asked interview questions related to AWS DynamoDB here in this blog.

1.What is DynamoDB?

DynamoDB is a NoSQL database offered by Amazon Web Services (AWS) that is designed for fast and predictable performance at any scale.

It guarantees millisecond latencies for DynamoDB operations and allows for a 10-20 millisecond latency range.

2.What is the purpose of DynamoDB?

The purpose of DynamoDB is to manage and store large amounts of data in a scalable and cost-effective manner, while ensuring high availability and durability.

3.What type of data can be stored in DynamoDB?

DynamoDB can store a variety of data types, including strings, booleans, lists, sorted sets, and complex objects in JSON form.

4.What is the partition key in DynamoDB?

The partition key, called order I D, is a crucial decision in Dynamo that cannot be changed later. It is essential to consider whether your access pattern requires the order I D to be duplicated as the partition key, or if every record in your table will have an unique order I D.

5.What is the sort key in DynamoDB?

The sort key in DynamoDB is another key that is used to partition data across different nodes, providing extra levels of redundancy.

It is also used to arrange items within a partition and can be used for multiple queries.

6.What is the partition key and sort key for each entity in a DynamoDB table?

The partition key and sort key for each entity in a DynamoDB table specify how data is distributed across the partitions and how items are retrieved from the table.

The partition key is a unique identifier for each item, while the sort key is used to further filter results based on non-key attributes.

7.What is a GSI (Generated Search Index) in DynamoDB?

A GSI (Generated Search Index) is a secondary index that is automatically created by DynamoDB based on the data stored in the main table.

It allows for fast and efficient querying of data based on secondary attributes (non-key attributes).

8.How can GSIs be used in DynamoDB?

GSIs can be used in DynamoDB to perform various queries such as text queries, filtering by non-key attributes, and advanced text searches.

They can also be used for sparse indexing and filter conditions.

9.How does GSIs overloading work?

To query the GSI filter by name, the partition key is defined as the partition key of the table itself, and the sort key is pointed to the new date attribute.

10.How can data be accessed in DynamoDB?

Data can be accessed in DynamoDB through its APIs and ORMs, which can be communicated with restfully through an ORM or object relational mapper.

11.What are the basic operations that can be performed on a table in DynamoDB?

Basic operations that can be performed on a table in DynamoDB include scans, filtering, and queries.

The scan function returns everything, while the filter function applies a filter to the specified attributes. The query function allows for specific key fields, such as order ID and creation date, and can be run to retrieve both records.

12.What is caching in DynamoDB?

Caching in DynamoDB refers to the ability to attach caching to the database, using services like DAX or DynamoDB accelerator, with minimal changes to DynamoDB queries.

This allows data to be retrieved faster, as it can be cached in memory and accessed more quickly than if it had to be retrieved from the database every time it was requested.

13.What is best practices for data modeling with DynamoDB?

Best practices for data modeling with DynamoDB include identifying almost all access patterns for your application before designing your data model

spending time identifying the most common design patterns and deciding on the most suitable primary keys and indexes to satisfy these access patterns, and avoiding traditional relational data modeling and focusing on identifying the most essential access patterns for your application.

14.What is an Elasticsearch cluster in DynamoDB?

An Elasticsearch cluster is a way to perform text queries and advanced text searches in DynamoDB.

It triggers a stream when inserting, deleting, or updating records, and a lambda function intercepts this stream data to identify operations and index the data item in the Elasticsearch cluster.

15.What are the features of DynamoDB?

DynamoDB is designed to provide high performance, scalable applications that would not be possible with a traditional database system.

It offers features such as on-demand capacity mode, built-in support for asset transactions, on-demand backup, point-in-time recovery, and encryption at rest

16.What is the difference between on-demand and provisioned mode in DynamoDB?

On-demand mode allows users to pay for storage as requests come in, suitable for unpredictable workloads.

Provisioned mode allows users to set the capacity of their cluster at any given point in time, ensuring predictable performance.

17.What is the purpose of using an index in Dynamo?

Using an index in Dynamo allows for efficient querying on other columns, such as the origin country.

18.What are the main entities for the project management tool?

The main entities for the project management tool are organization, projects, and employees.

The primary key for the organization entity should consist of hash and range keys.

 20.What is the role of access patterns in data modeling?

Identifying access patterns for each entity is crucial for data modeling. This involves identifying the most common design patterns and deciding on the most suitable primary keys and indexes to satisfy these access patterns.

21.What is the recommended maintenance for DynamoDB?

Users are advised to perform vacuuming to make cells from which data has been deleted available for storage.

22.What is the inverted index used for entity relationships?

The inverted index is used to break down entity relationships into two one-to-many relationships.

23.What are the differences between relational and NoSQL databases?

Relational databases, such as MySQL, Oracle, and Microsoft SQL Server, use data normalization to split data across multiple tables for efficient storage.

However, these databases require more compute power for table joins and can degrade performance as the database scales.

NoSQL databases, on the other hand, are optimized for compute rather than storage, keeping duplicate copies of data and minimizing table joins to reduce compute power required to retrieve data.

They also provide flexible schemas, allowing items with different attribute numbers to be in the same table.

24.What is the purpose of a mental model shift in DynamoDB?

A mental model shift is necessary when accessing data in DynamoDB, as it requires a different approach to data management and querying.

25.How can data be accessed in DynamoDB?

Data can be accessed in DynamoDB through its APIs and ORMs, which can be communicated with restfully through an ORM or object relational mapper.

26.What are some of the programming languages that have ORMs available for DynamoDB?

Some of the programming languages that have ORMs available for DynamoDB include Java and Python.

27.What is RDS’s pricing model?

RDS’s pricing is generally cheaper than other databases, available under pay-as-you-go or reserved instance models.

28.What is sparse indexing in DynamoDB?

Sparse indexing is a technique used in DynamoDB to reduce the amount of data stored in the secondary index by only indexing items that meet certain criteria, such as budgetary restrictions. This can improve the performance of queries that filter by non-key attributes.

29.What is the main objective of the multi-tenant project management tool?

The main objective of the multi-tenant project management tool is to manage organization projects and assign employees within these projects.

30.What are the two read and write modes in Dynamo, and what do they do?

The two read and write modes in Dynamo are capacity or cost modes, which are important for determining database performance.

Now its time to give a try with MCQ’s Let’s go!!!

1) What is the primary key in DynamoDB?

A) partition key

B) sort key

C) index key

D) composite key

2) What is one advantage of using DynamoDB over a relational database?

A) Table joins

B) Flexible schemas

C) Data normalization

D) Scalability

3) Which AWS service enhances the performance of DynamoDB queries with minimal changes?

A) AWS CloudWatch

B) Amazon RDS

C) DynamoDB accelerator

D) Elasticsearch

4) What is the primary purpose of identifying access patterns in DynamoDB data modeling?

A) Efficient retrieval of data

B) Creating secondary indexes

C) Optimizing cost

D) Establishing relationships between entities

5) What type of consistency does DynamoDB provide by default?

A) Quorum consistency

B) Linearizability

C) Eventually consistent

D) Strong consistent

6) Which of the following best describes the difference between relational and NoSQL databases according to the passage?

A) Relational databases offer better scalability and performance than NoSQL databases

B) NoSQL databases provide ACID properties while relational databases do not

C) NoSQL databases have flexible schemas while relational databases require fixed schemas

D) Relational databases use data normalization and table joins which require more compute power, while NoSQL databases minimize joins and duplicate data to reduce compute requirements

7) What concept in DynamoDB allows for more efficient and cost-effective querying based on access patterns?

A) Local secondary index

B) Composite primary key

C) Primary index

D) Global secondary index (GSI)

8) Why is identifying access patterns crucial when data modeling with DynamoDB?

A) Access patterns determine the encryption type used by DynamoDB

B) It allows developers to design the most suitable primary and secondary keys to satisfy the application’s access patterns

C) Identifying access patterns enables point-in-time recovery in DynamoDB

D) DynamoDB requires access patterns to be identified before any data can be inserted

9) What is the purpose of using global secondary indexes (GSIs) in DynamoDB?

A) Required for time-to-live based record expiry

B) Enable text search capabilities in DynamoDB

C) Improved to write performance of DynamoDB tables

D) Allow efficient querying based on non-key attributes beyond what is possible with just the table’s primary keys

10) Which DynamoDB component consists of single data fields attached to items?

A) Records

B) Attributes

C) Columns

D) Tables

In this blog we explored some of the most frequently asked AWS DynamoDB interview questions and answers, covering key features like tables/key structures as well as global/local secondary index usage; by understanding these concepts you can effectively utilize AWS DynamoDB to meet the demands of your applications.