What is the structure of PostgreSQL?

PostgreSQL is a relational object-oriented database management system with a rich data structure. The main structural components of PostgreSQL include:

• Database clusters — a set of databases managed by a single PostgreSQL server.
• Databases — logical containers containing schemas.
• Schemas — namespaces containing tables, views, functions, and other objects.
• Tables — the primary data storage structures consisting of rows and columns.
• Indexes — structures to speed up searches within tables.
• Transactions and WAL (Write-Ahead Logging) — ensure data reliability and recovery.

Internally, PostgreSQL stores data in files on disk organized into pages (usually 8 KB), and also uses a buffer pool for caching data in memory. The architecture supports extensibility through user-defined data types, operators, and functions.