PostgreSQL vs DynamoDB for Solo Developers

Quick Comparison

PostgreSQL Overview

PostgreSQL is the relational database I default to for every project. Tables, rows, columns, foreign keys, joins, aggregations, JSONB, full-text search. It handles structured data with the reliability that comes from decades of production use. You model your data naturally, query it with SQL, and use the same skills across every project.

The ecosystem is massive. Every ORM supports Postgres. Every cloud provider offers managed Postgres. Tools like Supabase and Neon give you free hosted Postgres with extra features. You are never stuck, never locked in, and never short on documentation.

DynamoDB Overview

DynamoDB is AWS's fully managed NoSQL database. It stores data as key-value pairs or documents with single-digit millisecond performance at any scale. Amazon manages everything: servers, replication, backups, and scaling. You define tables, partition keys, sort keys, and indexes, then let AWS handle the rest.

The free tier gives you 25 GB of storage and enough read/write capacity for small applications. Pay-per-request mode charges only for the operations you perform, which keeps costs low for sporadic traffic. Provisioned mode gives predictable pricing for steady workloads.

DynamoDB powers Amazon.com itself, along with thousands of other high-traffic applications. At massive scale, it is one of the most reliable databases available.

Key Differences

Data modeling is where most people give up on DynamoDB. PostgreSQL lets you model data naturally: users table, orders table, products table, join them with SQL. DynamoDB requires you to think about access patterns upfront and design your table structure around them. Single-table design, composite keys, and GSIs (Global Secondary Indexes) are concepts you must learn before DynamoDB makes sense. This learning curve is steep and unintuitive for anyone coming from relational databases.

Querying is radically limited in DynamoDB. No joins. No GROUP BY. No subqueries. No ad-hoc WHERE clauses on arbitrary columns. You can only query efficiently using your partition key and sort key, or through indexes you define ahead of time. Need to find all orders over $100 from last month grouped by category? That is one SQL query in Postgres. In DynamoDB, you need a specifically designed index or a full table scan.

Fully managed is genuinely zero-ops. DynamoDB requires no server management, patching, backups, or scaling decisions. It just works. PostgreSQL, even with managed providers, requires some decisions about instance size, connection pooling, and backup strategies. For a developer who never wants to think about database operations, DynamoDB delivers on that promise.

AWS lock-in is total. DynamoDB is a proprietary AWS service. There is no way to run it outside AWS (DynamoDB Local is for testing only). If you ever want to leave AWS, you rebuild your entire data layer. PostgreSQL runs anywhere, on any cloud, on any VPS, even on your laptop.

Cost can surprise you. DynamoDB pricing depends on read/write units, storage, and data transfer. A poorly designed access pattern can make costs spike. Scanning a large table is expensive. PostgreSQL on a VPS has a flat monthly cost regardless of how many queries you run. For a solo developer learning the ropes, predictable pricing is safer.

When to Choose PostgreSQL

• You want flexible querying with SQL (joins, aggregations, ad-hoc queries)
• You value data modeling freedom without upfront access pattern design
• You want zero vendor lock-in
• You need reporting, analytics, or complex data relationships
• You want the simplest path from prototype to production

When to Choose DynamoDB

• You are building entirely within the AWS ecosystem
• Your access patterns are well-defined and will not change
• You need true zero-ops database management
• You are building a high-throughput application with simple key-value lookups
• You already understand DynamoDB's data modeling patterns

The Verdict

PostgreSQL is the better choice for solo developers by a wide margin. The 9/10 vs 5/10 gap reflects the reality that SQL gives you flexibility, DynamoDB's data modeling requires expertise that takes months to build, and AWS lock-in is a serious risk for someone who might want to switch providers later.

DynamoDB is powerful in the right context. If you are deep in the AWS ecosystem, understand single-table design, and your application fits the key-value access pattern, it performs brilliantly. But for a solo developer starting a project, PostgreSQL lets you model your data naturally, query it flexibly, and host it anywhere. Start with Postgres. If you specifically need DynamoDB's scale and ops model later, you will know it.