For example, wal_compression was a boolean before 15, then it changed to an enum type which allows different kind of compression algorithm.

Thanks for your tool, very helpful :)

Details

The current method to add a new version directly uses postgresql.conf to determine defaults. This was a bit awkward from the beginning and has a number drawbacks with maintainability and accuracy. This change should set the stage for a number of subsequent improvements.

Planned approach

Use a query against pg_catalog.pg_settings similar to this example. Create a Python script to dump to csv/json/something to parse back in. This calculates the postgresconf_line for matching current expectations, not sure that will make it to the final version. Also calculating a few bool indicators that may be helpful.

SELECT name, setting, context, source, reset_val, boot_val,
		unit, category,
		name || ' = ' ||  setting AS postgresconf_line,
		short_desc,
		CASE WHEN name LIKE 'lc%'
				THEN True
			WHEN name IN ('application_name', 'TimeZone')
				THEN True
			ELSE False
			END AS frequent_override,
		CASE WHEN boot_val = reset_val THEN True 
			ELSE False 
			END AS system_default,
		CASE WHEN reset_val = setting THEN False 
			ELSE True
			END AS session_override
	FROM pg_catalog.pg_settings
;

Possible future improvements

• Handle case when a GUC type is different #7
• Display differences between server config (postgresql.conf) & user config (SET TimeZone = 'America/Denver';)
• Allow for extension specific config, e.g. pg_stat_statements, Timescale. <-- Should be category='Customized Options'
• Allow for config specific to Pg variants, e.g AWS RDS, MS Azure, etc.