acceptedJune 15, 2024

Use PostgreSQL over MongoDB for Transactional Data

databasebackendfintech

Context

Needed a database for a fintech application handling financial transactions

Decision

Chose PostgreSQL for ACID compliance and strong data integrity

Consequences

Pro: Full ACID compliance ensures transaction integrity
Pro: Mature ecosystem with excellent tooling
Pro: Strong type system with constraints
Con: Schema migrations require careful planning
Con: Less flexibility for document-like data

Context

When building a fintech application that handles financial transactions, data integrity is paramount. We evaluated MongoDB and PostgreSQL as primary database options.

Decision Drivers

Data Integrity: Financial data must be consistent and accurate
ACID Compliance: Transactions need atomicity, consistency, isolation, durability
Query Flexibility: Complex reporting and analytics requirements
Team Expertise: Team had more experience with SQL databases

Considered Options

MongoDB

Flexible schema for rapid iteration
Horizontal scaling built-in
Document model fits some use cases

PostgreSQL

Strong ACID guarantees
Mature ecosystem
Excellent JSON support when needed
Better for relational data

Outcome

PostgreSQL was chosen. After 6 months in production:

Zero data inconsistencies
Complex queries perform well with proper indexing
Schema migrations handled smoothly with tools like Prisma

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