PostgreSQL Configuration Precedence

Configuration / Guide 15 of 47 / Advanced

• OSUbuntu 26.04 LTS
• PostgreSQL18.6-0ubuntu0.26.04.1
• TimeAbout 13 min

sourcefile and sourceline are visible only to superusers and roles granted pg_read_all_settings. As an ordinary role they come back empty, which is a restriction rather than a bug.

• PackagingDebian cluster layout

This guide includes

Use this when you need to know where a live value actually came from. This matters because pg_settings.source names it - default, configuration file, or ALTER SYSTEM - so precedence is readable rather than reasoned about.

• asking where each value came from, for four settings at once
• handing a setting back to the defaults with ALTER SYSTEM RESET
• reading precedence off the server instead of inferring it

Before you start

• Settings changed by the previous guides in this track.

1. 1

   Ask where each value came from

2. 2

   Hand a setting back to the defaults

Official sources

• PostgreSQL 18 Documentation - Setting Parameters
• PostgreSQL 18 Documentation - pg_settings
• PostgreSQL 18 Documentation - ALTER SYSTEM
• PostgreSQL 18 Documentation - Resource Consumption