You can access a remote Heroku PostgreSQL database through a psql
session
using the following command:
heroku pg:psql --app my-app
That opens an interactive psql session.
If instead you'd like to run a single SQL script against that remote database, you can redirect that script to the connection.
heroku pg:psql --app my-app < query.sql
The results of running that SQL will be written to stdout.
You can take this a step further by redirecting the output into another file so that you can review and search the results at your convenience, rather than only having them appear in your terminal.
heroku pg:psql --app my-app < query.sql > results.out