manage-major-versions-with-brew-and-direnv.md

Manage Major Versions With Brew and Direnv

I can install multiple major versions of PostgreSQL to my machine with brew with commands like the following:

$ brew install postgresql@14
$ brew install postgresql@16
$ # ...

I can then start and stop specific Postgres server versions using the brew services start/stop commands. Let's say 14 is running, but I want to switch to 16.

$ brew services stop postgresql@14
$ brew services start postgresql@16

Then I can use direnv to manage the Postgres client (bin directory) that gets used for certain projects. This way when I run a command like pg_dump or psql it will use the one associated with a specific major version of Postgres.

Assuming I already have direnv installed, I can add a .envrc to my project with the following line:

PATH_add /usr/local/opt/postgresql@16/bin

And then tell my system that the changes to this file are allowed to be sourced by direnv:

$ direnv allow .

That's it. Now I have PostgreSQL 16 (client and server) ready to use for my current project.