Book Image

AWS Certified Database – Specialty (DBS-C01) Certification Guide

By : Kate Gawron
5 (1)
Book Image

AWS Certified Database – Specialty (DBS-C01) Certification Guide

5 (1)
By: Kate Gawron

Overview of this book

The AWS Certified Database – Specialty certification is one of the most challenging AWS certifications. It validates your comprehensive understanding of databases, including the concepts of design, migration, deployment, access, maintenance, automation, monitoring, security, and troubleshooting. With this guide, you'll understand how to use various AWS databases, such as Aurora Serverless and Global Database, and even services such as Redshift and Neptune. You’ll start with an introduction to the AWS databases, and then delve into workload-specific database design. As you advance through the chapters, you'll learn about migrating and deploying the databases, along with database security techniques such as encryption, auditing, and access controls. This AWS book will also cover monitoring, troubleshooting, and disaster recovery techniques, before testing all the knowledge you've gained throughout the book with the help of mock tests. By the end of this book, you'll have covered everything you need to pass the DBS-C01 AWS certification exam and have a handy, on-the-job desk reference guide.
Table of Contents (24 chapters)
1
Part 1: Introduction to Databases on AWS
Free Chapter
2
Chapter 1: AWS Certified Database – Specialty Overview
5
Part 2: Workload-Specific Database Design
12
Part 3: Deployment and Migration and Database Security
16
Part 4: Monitoring and Optimization
20
Part 5: Assessment
21
Chapter 16: Exam Practice

Querying and scanning a DynamoDB table

DynamoDB has two different methods of retrieving data:

  • Query
  • Scan

DynamoDB is designed to be queried only by the key attributes. This means that if you wanted to query an attribute that wasn't a part of the key, then you would need to scan the entire table. This is fine for small tables, but as they grow in size the performance of the queries will rapidly decline. If you are from a SQL database background you can think of this in similar terms to a query being run against a table without an index. In addition to performance concerns, in DynamoDB, the more data you access in a table the more it costs, so queries that involve scanning the entire table can become costly. A query method can only be used if you are querying against the partition key, and a scan method is used if you are not using the partition key.

Let's take a look at an example using our high score table. If we want to get the high score for a player...