A guide to hiring a DynamoDB developer
DynamoDB is a managed database from Amazon Web Services. It stores items in tables, finds them by key and runs without servers for you to look after. It is used in shopping carts, user profiles, sessions, device data, games and many serverless apps. It rewards careful planning and punishes guesswork. Below you will find what the job involves, how to test a candidate and how to run the work with someone remote. It suits founders and team leads who want a data layer that stays fast and affordable as use grows.
How DynamoDB thinks
In a SQL database you describe your data, then ask it anything. In DynamoDB you do the opposite. You decide first which questions the app will ask, then shape the table so each question is a quick lookup by key. Every item has a partition key and often a sort key, and those two choices decide how data is spread and how it can be read. Extra search options come from secondary indexes, each of which adds cost.
Why design matters so much
A badly planned table works at first and hurts later. If many requests hit the same key, that part of the table slows down. If the app has to scan the whole table to answer a question, reads become slow and costly. If a new feature needs a query the table was not built for, the fix can mean a rewrite. A DynamoDB developer avoids these traps by listing the access patterns up front and by testing them with realistic data.
The jobs people hire for
The first job is a new data layer for a product, often next to Lambda functions and an API. The second job is a rescue. A table is slow, throttled or surprisingly costly, and someone must find out why. The third job is migration, moving from SQL or MongoDB to DynamoDB or the other way round. The fourth job is event work, where changes in a table feed other systems such as search, email or reporting.
How a DynamoDB developer differs from other roles
An AWS developer covers the whole cloud setup, and DynamoDB is one tool among many. A back-end developer writes the application and may use several databases. A Node.js developer often writes the code that calls DynamoDB. A DynamoDB developer is the person to bring in when the table design and its cost are the hard part. On a larger project the specialist often works next to one of these roles.
When a DynamoDB developer makes sense
- You are building a serverless app and want a database with little upkeep.
- Your app has a few clear lookups that must stay fast under heavy traffic.
- An existing table is slow, throttled or more costly than expected.
- You plan to move data from another database and want the design done well.
- You need changes in a table to trigger other work, such as messages or updates.
If your data has many links and you need flexible reports, a relational database may serve you better. A developer who says so early is saving you money.
Check the data rules first
Tables often hold customer or payment details, and rules about where and how data is stored may apply to you. Decide with your developer which fields go into the table, which region holds them, how long they are kept and who may read them. Write it down. If the data is sensitive, speak to a lawyer or privacy adviser before you go live.
Reading a DynamoDB developer’s background
Ask for a project where the design was tested under real traffic or changed after launch. Good answers explain the keys, the queries and what the developer would do differently now. Be careful with a background that lists AWS names only. Anyone can create a table, while a design that survives growth takes experience with access patterns, indexes and cost.
Interview questions to try
- How do you decide on a partition key and a sort key for a new table?
- Our app now needs a new search. How do you add it to a live table?
- One customer sends far more traffic than the rest. What problem does that cause?
- How do you tell if a table should use on-demand or provisioned capacity?
- When would you advise us not to use DynamoDB?
Strong replies include reasons and a real example. Take care with anyone who treats DynamoDB like a SQL database with a different name.
Run a small paid exercise
Set the same short job for each finalist, taken from your actual backlog. Options include designing a table for three of your real queries, reviewing a costly table and listing fixes, or planning the move of one SQL table. Pay for their time. Compare how the person explains the keys, how they handle odd cases and whether they ask about your traffic.
Agree how the data is kept safe
Databases need care over time. Agree who reviews capacity and cost, how changes to a live table are tested and how you will be told when a table is throttled. Ask for the setup to be kept as code, with a short note on every table. Keep the cloud account in your company’s name, use narrow permissions for each app and switch off their access at the end of the project.
Settling in
Take your developer through the screens, jobs and reports that touch the data. A weekly check-in and one shared board of tasks keep the work visible. Share the awkward cases early, such as one very busy customer or a report that needs many filters, since those usually decide the design.
Mistakes to avoid
- Designing the table like a SQL database and fixing it later.
- Adding many indexes without checking what they add to the bill.
- Scanning whole tables in the app to answer ordinary questions.
- Skipping backups and a restore test because the service is managed.
Need a wider skill set? You can also browse our AWS developers for the full cloud setup, or our Node.js developers for the code that calls your tables.