Editing PostgreSQL (section)

=== Schemas ===
PostgreSQL schemas are [[namespace]]s, allowing objects of the same kind and name to co-exist in a single database.
They are not to be confused with a
[[database schema]]—the abstract, structural, organizational specification which defines how every table's data relates to data within other tables.
All PostgreSQL database objects, except for a few global objects such as [[#Security|roles]] and [[tablespace]]s, exist within a schema.
They cannot be nested, schemas cannot contain schemas. 
The permission system controls access to schemas and their content.
By default, newly created databases have only a single schema called ''public'' but other schemas can be added and the public schema isn't mandatory.

A {{code|search_path}} setting determines the order in which PostgreSQL checks schemas for unqualified objects (those without a prefixed schema). By default, it is set to {{code|$user, public}} ({{code|$user}} refers to the currently connected database user). This default can be set on a database or role level, but as it is a session parameter, it can be freely changed (even multiple times) during a client session, affecting that session only.

Non-existent schemas, or other schemas not accessible to the logged-in user, that are listed in search_path are silently skipped during object lookup.

New objects are created in whichever valid schema (one that can be accessed) appears first in the search_path.