SaaS Database Design: PostgreSQL vs NoSQL

The Database Debate

Every project hits this question.

PostgreSQL or MongoDB?

We choose PostgreSQL. Always.

Why PostgreSQL Wins

1. Relational Data is Natural

Users have organizations. Organizations have subscriptions. Subscriptions have invoices.

This is relational data. SQL handles it naturally.

2. Transactions

When a user signs up, we need to:

• Create user record
• Create organization record
• Create subscription record

All or nothing. That's a transaction.

MongoDB can do transactions. PostgreSQL does them easily.

3. JSON When You Need It

PostgreSQL has JSONB.

Need flexible schema? Store JSON.

Need structured data? Use tables.

Best of both worlds.

4. Full-Text Search

PostgreSQL has built-in search.

No Elasticsearch needed for most use cases.

5. Supabase

We're Supabase fans. It adds:

• Real-time subscriptions
• Auto-generated APIs
• Row-level security

All on PostgreSQL.

When MongoDB Makes Sense

1. Document-Heavy Data

CMS content. Blog posts. User-generated content.

Schema-less is convenient here.

2. Rapid Prototyping

Need to iterate on schema quickly.

MongoDB flexes easier.

3. Massive Scale

If you're Google, MongoDB makes sense.

For everyone else? PostgreSQL scales plenty.

The Migration Question

"We might need to switch later."

You won't.

Schema changes in PostgreSQL are manageable.

And Supabase makes migrations easy.

The Decision Framework

The Honest Answer

For SaaS MVP: PostgreSQL.

It's proven. It's scalable. It's everywhere.

MongoDB is powerful. But PostgreSQL is enough.