How to Reload Configuration in PostgreSQL Quickly

To reload PostgreSQL configuration without restarting the server, use the SQL command SELECT pg_reload_conf();. This command tells PostgreSQL to re-read its configuration files and apply changes immediately.

Syntax

The command to reload PostgreSQL configuration is a simple SQL function call:

• SELECT pg_reload_conf(); - This tells PostgreSQL to reload its configuration files.

No parameters are needed. It returns true if the reload was successful.

sql

SELECT pg_reload_conf();

Output

 pg_reload_conf 
--------------
 t
(1 row)

Example

This example shows how to reload the PostgreSQL configuration after changing postgresql.conf or pg_hba.conf without restarting the server.

sql

/* Connect to your PostgreSQL database and run: */
SELECT pg_reload_conf();

Output

 pg_reload_conf 
--------------
 t
(1 row)

Common Pitfalls

Some common mistakes when reloading PostgreSQL configuration:

• Editing configuration files but forgetting to reload with pg_reload_conf(), so changes do not take effect.
• Trying to reload configuration that requires a full server restart (e.g., changing shared_buffers), which pg_reload_conf() cannot apply.
• Running the reload command without sufficient database privileges (you need to be a superuser).

sql

/* Wrong: Editing config but not reloading */
-- Changes won't apply until reload or restart

/* Right: Reload config after editing */
SELECT pg_reload_conf();

Quick Reference

Summary of PostgreSQL configuration reload commands:

Command	Description
SELECT pg_reload_conf();	Reloads configuration files without restarting the server.
pg_ctl reload	Shell command to reload configuration (alternative to SQL).
System restart	Required for some settings that cannot be reloaded dynamically.

Key Takeaways

Use SELECT pg_reload_conf(); to reload PostgreSQL config without restarting.

Not all config changes can be applied by reload; some require a full restart.

You must have superuser privileges to run the reload command.

Reloading applies changes from postgresql.conf and pg_hba.conf.

Alternatively, use pg_ctl reload from the command line to reload config.