Friday, March 14, 2008

Getting bit by MySQL Dates

Yesterday morning, Jack sent out a rather perplexing problem to Josh and myself.

Basically, he reported, this query doesn't return any results, despite there being plenty of valid records:

select * from injections where DATE(created_at) = DATE('2008-03-11');

And this query returns the expected records:

select * from injections where DATE(created_at) = DATE('2008-02-18');

The only difference between the two queries is the date provided. Crazy.

But wait, it's gets worse!

This query yields 293 rows (distinct days):

select distinct DATE(created_at) from injections;

While this one only returns 277 rows (days):

select distinct DATE(created_at) from injections where DATE(created_at) = DATE(created_at);

Josh provided some interesting links to MySQL documentation with tidbits like:
"MySQL automatically converts a date to a number if the date is used in a numeric context"
"However, this conversion is subject to the following exceptions: ... For these exceptional cases, the comparison is done by converting the objects to strings and performing a string comparison."
and this one, which I suspect is the culprit:
"A microseconds part is allowable in temporal values in some contexts, such as in literal values, and in the arguments to or return values from some temporal functions."
I emphasized the use of the word "some" in that quote. When an API is sometimes consistent - an oxymoron if I've ever heard one - it should set off the klaxons in your noggin.

We didn't solve the puzzle, but Jack did find a clever resolution: turns out that "created_at LIKE '2008-03-11%'" is about 10% faster.

Friday, February 22, 2008

Rails Scales

Last month, Stewart dropped me a little note...
"I've heard a few people mention that they heard that Rails doesn't scale [...] any suggestions on how we might alleviate their doubt?"
So I rallied the troops (Jack and Josh) and we set out on a little informal fact-finding mission. Here's what we've come up with thus far...

How 7 Mongrels Handled a 550k Pageview Digging

Not a lot of in-depth analysis here, just an impressive scaling success story with a pretty bar chart of the traffic load and an itemization of the hardware and software involved along with costs.

It's boring to scale with Ruby on Rails

Granted, this one is written by the man himself, Mister Rails, so you have to take it with a grain of salt, but he hits upon the common themes, which are caching, load balancing, and:
"Scaling the database is the `hard part'"
Unfortunately he gets a little off track in the second half of the essay and goes into the cost analysis of productivity and happiness, which is where you'll lose the attention of most investors.

Scaling Twitter: Making Twitter 10000 Percent Faster

I love the High Scalability blog; it's the dessert of my weekly reading. Granted Twitter still has its problems to this day, but you can't deny its monumental achievement in wide-spread adoption and ungodly levels of traffic. In addition to the aforementioned staples of caching, load balancing, and database optimization, they add partitioning and queueing to the mix.

Engine Yard Bets Big on Rubinius

What does this have to do with the scalability of Rails? Well nothing explicit in the article, but it supports two important movements that will eventually lead to a greater good.

First of all, Rubinius is one of three now mainstream Ruby implementations (the other two being Matz's original and Sun's JRuby). Competition here is good. This means better, faster, more stable Ruby environments, which will translate into a faster and more stable Rails.

Secondly, Rubinius is eventually going to lead to mod_rubinius, which will lead to even more scalability of the Rails platform by allowing us to leave separate single-process servers (like Mongrel) on the wayside.

Personally my money is on JRuby (and Glassfish) for the long haul; if you haven't checked out Glassfish yet, you're doing yourself a disservice!

Benchmark Invests in RoR Provider

Pretty much a no-brainer here. Benchmark Capital invested $3.5 million into Engine Yard, whose main business is Rails hosting.

Riding the Rails with WebSphere

If Glassfish is a little too cutting-edge for you, and you're all about being "enterprisey", then IBM's WebSphere is probably right up your alley.

At this point, between IBM and Sun's support of Ruby and Rails, and the multi-million dollar investments other Rails-based ventures are receiving, I'm beginning to wonder how savvy are these potential investors Stewart is getting flak from.

But we're not done yet...

Can Rails Scale? Absolutely!

This article is a pretty good round-up of the more recognizable names using Rails, such as Yellow Pages, Basecamp, and the infamous Twitter, as well as a rehashing of the same old story: caching, spreading the load, and tuning your database.

Friends for Sale Architecture - A 300 Million Page View/Month Facebook RoR App Todd Hoff's picture

Here we are again at my favorite feed, High Scalability, with another Rails scalability success story. This time it's a Facebook app, and a rather popular one at that. I won't spoil the surprise for you, because their is no surprise -- it's the same old story: cache, distribute, and:
"The most important thing we learned is that your scalability problems is pretty much always, always, always the database."

So in summary, there's plenty of good ammunition out there against the naysayers, and soon there will be one more when AdPickles launches and sets a whole new bar by which Rails scalability will be measured. No pressure Jack and Josh.

Wednesday, January 16, 2008

Hyphenated URLs in Rails

The Problem

Rails, by default, produces underscored URLs for multi-word methods and controllers. For example, a controller by the name of ContactUs with the method about_advertising will respond, with the default routing, to the path /contact_us/about_advertising. This is all well and good except when it comes to search engines. Underscores are seen, at least by Google at the moment, as part of a word, whereas hyphens (dashes) are seen as word separators. This means that our above path will hit for searches on "contact_us" and "about_advertising" but not for "contact" or "advertising". That's no good! How can we get Rails to use /contact-us/about-advertising so that our site might get indexed for the keyword "advertising"?

Action Names

Fixing the action name is easy enough as hyphens are valid characters in method names. Well, almost-- hyphens may be valid in method names, but they are not valid in symbols, which means that we can't use the standard "def" syntax to declare methods with hyphens in their names. To get around that, we turn to define_method. To change /contact_us/about_advertising to /contact_us/about-advertising, we can change the method declaration from:
def about_advertising
define_method('about-advertising') do

Controller Paths

It looks like we are halfway to where we want to go, but the controller part of the path turns out to be a more difficult part of the problem. There is no way, at least that I know of, to use an underscore in a class name. Therefore, we turn to Rails routing for some help. The easiest solution is to create a special route for the ContactUs controller in config/routes.rb as follows:

ActionController::Routing::Routes.draw do |map|
map.connect '/contact-us/:action/:id', :controller => 'contact_us'

and we get /contact-us/about-advertising. And we're done! Well, not quite. Having to add route entries for every multi-word controller is no fun, certainly not very DRY, and doesn't handle the RESTful map.resources. Enter hyphenated_controller_routes, the plugin I wrote to address those problems, and the reason for this blog post.

Hyphenated Controller Routes

The plugin, located at can automatically create hyphenated routes for all multi-word controllers, and can update map.resources to generate hyphenated URLs for multi-word resources. After installing the plugin, update config/routes.rb to make use of map.add_hyphenated_routes() and map.use_hyphenated_resources() as desired.

An example config/routes.rb:

ActionController::Routing::Routes.draw do |map|

#a resource that will be mapped with an underscore
map.resources :non_hyphenated_resources

#turn on hyphenated resources

#all following resources will use hyphens (contact-us)
map.resource :contact_us

# add hyphenated routes with higher priority than the default routes

# Install the default routes
map.connect ':controller/:action/:id.:format'
map.connect ':controller/:action/:id'


Saturday, November 10, 2007

Nested ActiveRecord Relationships and Validation Conundrum

I ran into a bit of a pickle earlier this week with some models and their relationships.

The Situation

* A partner has an account.

* An account has an address.

* Accounts do not require an address; it's optional.

* Partners do require an address.

The Problem

So how do I enforce the presence of an address for the account assigned to the partner?

My First Attempt

My first thought was to break the encapsulation and create a direct partner-to-address relationship. Then I came up with the clever hack of keeping the partner-address in sync with the account-address during assignment, so when you set the address for the partner, it would automatically set the account to the same address. But it just didn't sit right with me; it wasn't the typical Ruby on Rails elegance I had come to expect. So I reached out to my partner in crime (Jack Danger) and asked for his opinion.

A More Elegant Idea

Jack suggested a more elegant simplification of just validating the presence of the address from the partner level like so:
validates_presence_of :address

def address
account && account.address
Now that's the simplicity and elegance I've come to expect from a Ruby on Rails application.

A Possible Third

But Jack also took it a step further and suggested subclassing account and making address required, so we'd have two types of accounts, one with optional addresses and one with required addresses. That might be even less code and arguably more elegant, but my gut just tells me it's a little less of a hack than my original attempt and not quite as pure as his first suggestion.

Wrapping Up

I went with Jack's first suggestion and I'm satisfied with the results, but I'm curious to hear if anybody else has tackled the same, or similar, problem, and how they solved it.

Saturday, October 20, 2007

The future is green

No, I'm not talking about switching from my fossil fuel burning automobile to a hydrogen powered motorcycle. At least not yet. I am talking about pickles. adPickles. adPickles has started the design of its B2B platform. Things are looking pretty interesting right now. More adPickles info to come...

Thursday, September 13, 2007

adPickles and Rails - A beautiful marriage!

Using Rails to develop the adPickles web site was a smart choice. It seems that some of the brightest and best talent in the business has adopted Rails as a tool in their arsenal. And some of those brightest, I am proud to say, are the folks who are putting this project together. Another smart technical choice... png vs. jpg gave us freedom to expand our design horizons. Rails and adPickles. A great marriage indeed.

Thursday, July 19, 2007

The Midas Touch

Stewart Padveen has the Midas Touch when it comes to web companies. I've spent the last twelve years of my career designing and deploying the technologies that drove two of his companies (HotOffice and Nutrio). While I was busy doing that, he started two more successful ventures (MotionPoint and Firmagen). He pitched his latest idea to me at the beginning of this year and it sounded like another winner; I knew I had to be involved.

Although I've cut my teeth on Java and "the enterprise", a couple years back I started dabbling in a little gem (if you'll excuse the pun) called Ruby; a spectacularly elegant programming language. Then some crazy ambitious young Dane came along and built on top of it an even more wonderful web framework named Rails. It was a match made in Heaven and I fell in love immediately.

And speaking of perfect matches, AdPickles and Ruby on Rails make a very cute couple. The project has made tremendous progress thanks to this framework and the tight-knit community of brilliant supporters and contributors, and most of all Jack Danger Canty, their dedicated wizard. Not since the Perl years of yore have I seen such blur of productivity.

But the back-end isn't where all the magic happens. There's a client piece to this puzzle as well. I won't spill too many beans here, lest Stewart chastise me, but let me say that Windows is a cruel mistress, and the impressive skills of Aaron Cody have managed to tame that shrew.

Mark my words, and bookmark this feed, this is going to be another rocket ride to the stars.