ActiveRecord Optimization with Scrooge - igvita.com

Database connections are not thread-safe. That's why ActiveRecord uses a separate database connection for each thread.

For instance, the following code uses 3 database connections:

3.times do
  Thread.new do
    User.first # first databa...

Store schema-less data in MySQL.

Use this scope:

class Stick
  named_scope :shuffled, lambda {
    last_record = last
    { :conditions => [ 'id >= ?', rand(last_record.id) ] } if last_record
  }
end

You can now pick a random stick by saying

Stick.s...

Using Scenic, you can bring the power of SQL views to your Rails application without having to switch your schema format to SQL. Scenic provides a convention for versioning views that keeps your migration history consistent and reversible and av...

Re-creating a complex ActiveRecord scenario quickly without setting up a full-blown Rails app can come in handy e.g. when trying to replicate a presumed bug in ActiveRecord with a small script.

# Based on http://www.jonathanleighton.com/artic...

There is a way to use multiple databases in Rails.
You may have asked yourself how you're able to keep your test databases clean, if you're running multiple databases with ful...

If you ever need to restore exact records from one database to another, Marshal might come in handy.

Marshal.dump is part of the ruby core and available in all ruby versions without the need to install anything. This serializes complete ruby ...

When requests arrive at the application servers simultaneously, weird things can happen. Sometimes, this can also happen if a user double-clicks on a button, for example.

This often leads to problems, as two object instances are modified in paral...

A check if two date or time ranges A and B overlap needs to cover a lot of cases:

1. A partially overlaps B
2. A surrounds B
3. B surrounds A
4. A occurs entirely after B
5. B occurs entirely after A

This means you actually have to check that:

...

I followed this nice guide Connecting to MSSQL with Ruby on Ubuntu - lambie.org until I ran in the following errors:

irb(main):001:0> require "dbi"; ...