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📚 High Performance PostgreSQL for Rails

Rideshare is the Rails application supporting the book "High Performance PostgreSQL for Rails" http://pragprog.com/titles/aapsql, published by Pragmatic Programmers in 2024.

Installation

Prepare your development machine.

🎥 Installation - Rideshare on a Mac, Ruby, PostgreSQL, Gems

Homebrew Packages

First, install Homebrew.

Graphviz

brew install graphviz

Ruby Version Manager

Before installing Ruby, install a Ruby version manager. The recommended one is Rbenv. Run:

brew install rbenv

PostgreSQL

PostgreSQL 16 or greater is required. Installation may be via Homebrew, although the recommended method is Postgres.app

PostgresApp

  • Once installed, from the Menu Bar app, choose "Open Postgres" then click the "+" icon to create a new PostgreSQL 16 server

Ruby

Run cat .ruby-version from the Rideshare directory to find the needed version of Ruby.

For example, if 3.2.2 is listed, run:

rbenv install 3.2.2

Run rbenv versions to confirm the correct version is active. The current version has an asterisk.

  system
* 3.2.2 (set by /Users/andy/Projects/rideshare/.ruby-version)

Running into rbenv trouble? Review Learn how to load rbenv in your shell using rbenv init.

Bundler and Gems

Bundler is included when you install Ruby using Rbenv. You're ready to install the Ruby gems for Rideshare.

Run the following command from the Rideshare directory:

bundle install

Rideshare Development Database

⚠️ This scripts expects PostgreSQL version 16. If you see syntax errors with underscore numbers like 10_000, it's probably from using an older version that doesn't support that number style.

⚠️ Normally in Ruby on Rails applications, you'd run bin/rails db:create to create the development and test databases. Don't do that here. Rideshare uses a custom script.

The script is called db/setup.sh. Don't run it yet. The video below shows common issues for this section.

🎥 Rideshare DB setup. Common issues running db/setup.sh

Before you run it, let's set some environment variables. Open the file db/setup.sh and read the comments at the top for more info about these env vars:

  • RIDESHARE_DB_PASSWORD
  • DB_URL

⚠️ The script generates a password value using openssl, assuming it's installed and available.

Once you've set values, before running the script, run echo $RIDESHARE_DB_PASSWORD (and echo $DB_URL) to make sure they're set.

Once both are set, you're ready to run the script.

Let's capture the output of the script. Use the command below to do that. The script output goes into output.log file so we can more easily review it for errors.

sh db/setup.sh 2>&1 | tee -a output.log

Since you set RIDESHARE_DB_PASSWORD earlier, create or update the special ~/.pgpass file with the password you generated. This allows us to put the PostgreSQL user in the connection string, without needing to also supply the password.

Refer to postgresql/.pgpass.sample for an example, and copy the example into your own ~/.pgpass file, replacing the password with your generated one.

When you've updated ~/.pgpass, it should look like the line below. The last segment (2C6uw3LprgUMwSLQ below) is the password you generated.

localhost:5432:rideshare_development:owner:2C6uw3LprgUMwSLQ

Run chmod 0600 ~/.pgpass to change the file mode (permissions).

Finally, run export DATABASE_URL=<value from .env>, getting the value from the .env file in this project, set as the value of the DATABASE_URL environment variable.

Confirm that's a non-empty value by running echo $DATABASE_URL.

Once DATABASE_URL is set, we'll use it as an argument to psql to connect to the database. Run psql $DATABASE_URL to do that.

Once connected, you're good to go. If you'd like to do more checks, expand the checks and run through them below.

Installation Checks

From within psql, run this:

SELECT current_user;

Confirm user owner is displayed.

owner@localhost:5432 rideshare_development# select current_user;
 current_user
 --------------
  owner

From psql, run the describe namespace meta-command:

\dn

Verify the rideshare schema is displayed.

owner@localhost:5432 rideshare_development# \dn
  List of schemas
   Name    | Owner
-----------+-------
 rideshare | owner

Now that you've confirmed the owner user and the rideshare schema have been set up correctly, you can run the migrations to create Rideshare's tables.

Run Migrations

Run migrations the standard way:

bin/rails db:migrate

Run the describe table meta command next: \dt. Rideshare tables like users, trips are listed.

Note that migrations are preceded by the command SET role = owner, so they're run with owner as the owner of database objects.

See lib/tasks/migration_hooks.rake for more details.

If migrations ran successfully, you're good to go!

Data Loads

To load some sample data, check out: db/README.md

Development Guides and Documentation

Troubleshooting

The Rideshare repository has many README.md files within subdirectories. Run find . -name 'README.md' to see them all.

User Interfaces

Although Rideshare is an API-only app, there are some UI elements.

Rideshare runs PgHero which has a UI.

Connect to it:

bin/rails server

Once that's running, visit http://localhost:3000/pghero in your browser to see it.

Screenshot of PgHero for Rideshare