PostgreSQL vs MySQL vs SQLite: Selecting the Optimal Database Engine for Production SaaS

Selecting a primary persistence engine is among the most consequential technical decisions in product engineering. Changing databases in a live system with millions of rows is painful, risky, and expensive.

For years, the default advice was simple: use PostgreSQL for complex relations, MySQL for high-velocity reads, and SQLite only for local development or mobile devices. In 2026, advances in storage hardware (NVMe), write-ahead logging (WAL), and distributed replication have upended these historical assumptions.

Detailed Performance and Capability Matrix

+------------------+-------------------+-------------------+--------------------+
| Feature          | PostgreSQL 16+    | MySQL 8.4+        | SQLite 3.45+ (WAL) |
+------------------+-------------------+-------------------+--------------------+
| Concurrency      | Multi-version MCC | Row-level locking | Single-writer, MVCC|
| JSON Queries     | Binary JSONB, GIN | Native JSON Docs  | JSON functions     |
| Deployment Model | Client-Server     | Client-Server     | Embedded In-Process|
| Memory Footprint | 64MB - Multiple GB| 128MB - MultipleGB| < 1MB              |
| Backup Complexity| pg_dump / WAL-G   | Percona XtraBackup| File copy / SQLite3|
+------------------+-------------------+-------------------+--------------------+

When SQLite Excels in Production

Modern SQLite operating in Write-Ahead Log (`WAL2`) mode can easily serve 5,000+ reads per second on modest cloud VMs with zero network round-trip latency. Coupled with tools like Litestream for real-time continuous streaming replication to S3, SQLite is remarkably viable for:

When PostgreSQL Is Inevitable

PostgreSQL remains the undisputed champion when your domain demands:

-- PostgreSQL Native Row-Level Security
ALTER TABLE orders ENABLE ROW LEVEL SECURITY;

CREATE POLICY tenant_isolation_policy ON orders
FOR ALL
USING (tenant_id = current_setting('app.current_tenant_id')::uuid);

Conclusion

Do not pick a database based on marketing hype. Align your persistence technology with your query profile, operational expertise, and recovery time objectives (RTO).