What data storage format is used in PostgreSQL database?

PostgreSQL uses its own binary data storage format, optimized for efficient access and management. Data in tables are stored in fixed-size pages (usually 8 KB), each containing multiple rows (tuples). Rows consist of fields serialized in binary form.

Additionally, PostgreSQL supports various data types, including complex ones, each with its own storage method. Indexes and other data structures are also stored in specialized formats for quick searching.

Thus, the storage format is binary, optimized for performance and reliability, rather than simple text or JSON.