Switch database from MySQL (ClearDB addon) back to PostgresSQL in Heroku

Had permission problems using ClearDB and figure it wasn't worth all the hassle of adding another layer of abstraction/configuration when Heroku already works with PostgreSQL out of the box. Here's how to switch back to PG.

# Remove addon
heroku addons:remove cleardb

# Set DATABASE_URL back to PG
heroku config | grep SHARED_DATABASE_URL # => postgres://XXX
heroku config:add DATABASE_URL='postgres://XXX'

ClearDB MySQL on Heroku gotcha

Didn't know that a rails project deployed on heroku was using ClearDB MySQL as production database - I just assumed that it's PostgreSQL on Heroku till I saw that ClearDB addon was used. Removing the addon and mysql gems and configuring config/database.yml did not saw the application switched back to PG. Read the ClearDB addon and realized that DATABASE_URL environment was set.

https://devcenter.heroku.com/articles/cleardb

Quickly checkout Git remote branch into a local branch

git checkout -b LOCAL_BRANCH origin/REMOTE_BRANCH

Codeblocks for Markdown

From Daring Fireball:

To produce a code block in Markdown, simply indent every line of the block by at least 4 spaces

At least 4 spaces... so that means 2 tabs if your tab is set to 2 spaces.

SQL dump for MySQL databases

backup:

mysqldump -u root DATABASE_NAME > sqldump.sql

restore:

mysql -u root DATABASE_NAME < sqldump.sql

Search and replace words in multiple files in Vim

Upgraded my project's factory girl and got some nasty warnings about Factory(:xxx) and Factory.create(:xxx) syntax being deprecated. I've been using the former for almost all of the specs so needed an easy way to search and replace words in multiple files in Vim.

:args app/models/*
:argdo %s/Factory(:/FactoryGirl.create(:/ge | update

Differences in Ruby's loading methods

load() - loads and reloads indiscriminately

autoload() - only loads when classes inside are first called upon

require() - loads only once, further calls are ignored

require_relative() - same as require() except file paths are explicitly relative