Enhancement Idea - Expose the active value of a parameter inpg_settings

Hi Hackers,

I would like to propose that we expose the "active" value of parameters in pg_settings, instead of "-1".  In this
examplebelow, when it's set to "-1" I need to know that autovacuum_work_mem is related to the setting of
maintenance_work_mem,so that I can determine that the actual setting is 64MB: 

postgresql.conf
===============
#autovacuum_work_mem = -1               # min 1MB, or -1 to use maintenance_work_mem
#maintenance_work_mem = 64MB            # min 1MB


pg_settings
===========
postgres=# SELECT name, setting, unit FROM pg_settings WHERE name IN ('autovacuum_work_mem','maintenance_work_mem');
        name         | setting | unit
----------------------+---------+------
autovacuum_work_mem  | -1      | kB
maintenance_work_mem | 65536   | kB
(2 rows)


I think it would make sense to create a new column called something like "active_setting", which will allow simple
verificationof the setting that's in use without having to know the specifics about the parameter's relationship with
others,and the version of PostgreSQL.  For parameters where "-1" is a real setting that has meaning (e.g.
log_min_duration_statement),then it should return "-1". 

I presume that as a part of running the server that we have already decoded what the active values should be, so I'm
askingif we can expose this data via the pg_settings view? 

Regards
Greg Clough

https://ipreo.com


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