Examples for Customized options

[W1M0R]

Postgres has support for extension variables:

This feature was designed to allow parameters not normally known to PostgreSQL to be added by add-on modules (such as procedural languages). This allows extension modules to be configured in the standard ways.

Custom options have two-part names: an extension name, then a dot, then the parameter name proper, much like qualified names in SQL. An example is plpgsql.variable_conflict.

Because custom options may need to be set in processes that have not loaded the relevant extension module, PostgreSQL will accept a setting for any two-part parameter name. Such variables are treated as placeholders and have no function until the module that defines them is loaded. When an extension module is loaded, it will add its variable definitions, convert any placeholder values according to those definitions, and issue warnings for any unrecognized placeholders that begin with its extension name.

Does pgx provide a way to add/register variables for an extension?

[eeeebbbbrrrr]

Hi there! pgx sure does. It provides a few safe wrappers into Postgres' GUC (grand unified configuraiton) system. Sadly, pgx' docs for this aren't great right now, but there's a fairly complete (and working!) example of all this in ZomboDB: https://github.com/zombodb/zombodb/blob/master/src/gucs/mod.rs

You'll need to register your GUC variables via the _PG_init() function, which you can see ZomboDB does here: https://github.com/zombodb/zombodb/blob/7d0635a6b1a857c937f871102d53bb688a7916ab/src/lib.rs#L29

I'd like to put together some examples for this in pgx' repo someday. It's a pretty nice feature.

[W1M0R]

Awesome @eeeebbbbrrrr! Thank you for your efforts to contribute such a helpful library/tool to the postgres ecosystem.

[Hoverbear]

I updated the issue title to reflect that this is an existing feature and the desire is for an example demonstrating the feature!