PostgreSQL's information_schema: A Standard Way to Query Database Metadata

PostgreSQL includes a built-in, read-only schema called information_schema that provides metadata about database objects such as tables, columns, constraints, and privileges. It follows ANSI/ISO SQL standards, meaning queries written against it are largely portable across other databases like MySQL, SQL Server, and MariaDB. The schema is permission-aware, automatically showing only the objects accessible to the current user, and its structure remains stable across PostgreSQL versions. Developers can use it to inspect table definitions, column data types, primary keys, and more using standard SQL SELECT statements. For deeper PostgreSQL-specific details — such as indexes or custom types — the native pg_catalog schema is recommended instead.