PostgreSQL

What it is

PostgreSQL is a mature open-source SQL database known for correctness, extensibility, and a strong ecosystem.

Key features

• SQL + extensions - Relational core with extensibility (types, functions, extensions).
• Transactions - ACID transactions and strong consistency.
• Indexing - Multiple index types and query planner features.
• Replication - Streaming and logical replication options.

Strengths

• SQL + extensions - Relational core with extensibility (types, functions, extensions).
• Transactions - ACID transactions and strong consistency.
• Indexing - Multiple index types and query planner features.

Trade-offs

• Scaling writes - Write scaling typically requires partitioning or sharding layers.
• Operations - Backups, upgrades, and tuning remain core responsibilities.
• Managed variance - Managed offerings differ in extension support and behavior.

Pricing

Open-source software. Direct license cost is zero; costs are typically infrastructure, operations, and optional paid support or hosting.