Database Visualization

Keeping documentation up-to-date is always a pain in the ass. I was recently working on updating our database diagrams and thought that there may be a way to automate the process.

I found 2 solutions:

1. XMI
2. RailRoad

For solution (1), it worked, but I had to tweak it slightly. Because we are using PostgreSQL, I had a problem when UmlDumper tried to execute current_database for the adapter. This works fine for the MySQL adapter, but no such function exists for the PostgreSQL adapter. I quickly hacked it and just replaced it with a general name for our database, as we didn't have to be dead-on here.

I was quite disappointed when Dia did not know how to open up the XMI file. So, searching around, I found a program called Umbrello. It works great. Unfortunately, I had all my UML classes, but no diagram! I had to drag and drop each one individually (I couldn't figure out how to drag them all at the same time T.T). I then manually added in all the lines and made it pretty. Not too bad, but it was partly automated and partly manual.

For solution (2), it worked great. I used a rake task to generate the svg files. I had several issues with this, which was the fact that RailRoad is used to diagram models in RoR, not the database. Hence, I ended up with a lot of relations that didn't exist in the database. This meant TONS of lines. The lines are also quite hard to follow as they constantly overlap and cross each other.

2 major issues I had was that there is a 1-to-1 relationship (for efficiency purposes). However, the diagram did not reflect this. For example, we have class A and B that are in a 1-to-1 relationship. A will have has_many relationships and so will B. However, the diagram showed that all of B's has_many relationships were related to A, not B. I couldn't figure out why.

The other issue was a logged bug. If the model ends in an 's', the diagram gets messed up. The diagram will automatically drop the trailing 's'. This created incorrect relationships.

For these 2 major issues, I was unable to use solution (2) in the end. However, if more improvements are made, I may give it another chance as the whole process was completely automated. If your interested, it also does Controller diagrams.

If anyone else has a better way of producing automated diagrams of their database or models, give me a shout. I'd love to hear other solutions.


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Google: AdWords Algorithm

Sorry, this isn't a post about Google's algorithm :P

But, there is news that they're planning to modify it! That's big news to people using AdWords. Go and check it out.

Quick summary:

- dynamic calculations of Quality Score at search time
- keywords are no longer labeled as "inactive for search"
- no more "minimum bids"... in comes "first page bid estimates"

In other words, Google wants more money ;)


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JavaScript Heaven

I stumbled across this amazing page of JavaScript tools. Enjoy!

http://www.smashingmagazine.com/2008/09/11/75-really-useful-javascript-techniques/


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Y Combinator

Y Combinator is a venture firm that specializes in funding startups in their early stages. I recently discovered their news section, which, as a technical person, I find very interesting. It is a Digg type site that gives links to interesting articles. Every so often, I will also see RoR articles on there. Check it out:

http://news.ycombinator.com/


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Ubuntu: Volume Problems

Recently, my audio has been much softer than it has been when I first installed Ubuntu. Even if I turn my volume up completely, the audio was only at a normal volume. I found this odd because before, when I turned it up, it would blast my ears off.

I managed to find out why! If you go to your Volume Control, Edit > Preferences, and select PCM. Then turn the PCM volume up to the desired level. Mine, for some reason, was set at a very low volume.

I'm not quite sure what happened, as I never played with my settings. My only guess is that some particular update fooled with the settings.


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BackgrounDrb.destroy

So we've been noticing some pretty odd things with BackgrounDrb lately. In spite of our previous fixes to BackgrounDrb, we've decided to give up on it. Why? Simply put: It's not working properly.

We've been checking the logs recently, and we've noticed way too many calls to our scheduled tasks. On the odd days, we'll get 3 or 4 extra calls when only 1 was scheduled. I don't know how to explain this, nor do I wish to find out, because frankly, I'm fed up with this.

I admit, it really was my fault for trying to use an overly complicated program to run something very simple. KISS - I know. I'm kicking myself in the ass for this now! Anyways, simple solution: cron. It's the most basic of basic schedulers. You can't go wrong here.

Luckily, all our functions were encapsulated in the models, so the logic didn't need to be changed. We ripped out the stuff in the BackgrounDrb worker and placed them in a rake file. We then called the rake tasks from the cron.

Very simple. Very clean.

Bye Bye BackgrounDrb!


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Sitemap

It's nice to have a sitemap that adheres to the Sitemap 0.90 protocol. In rails, this can be automatically generated. Unfortunately, you have to do some work.

I found 2 different ways:

1. using controllers
2. using rake

If your site is small, (1) works really well. It's as dynamic as it can be as the sitemap is generated on the fly. However, every time anyone visits that URL, you end up hitting the database for a fairly large call, memory-wise. If it's just legitimate people accessing it, they will access the URL when they need it, or on a periodic time frame. However, if you encounter malicious users (which there are many out there), they could easily overload your server.

(2) is not as up-to-date, but from my point of view, that's ok, especially if you update the files daily. The solution posted works well, but since out site takes advantage of BackgrounDrb, I thought I would modify it to work with BackgrounDrb instead of rake.

I created some self functions to do the database queries and handle the tasks in the rake. Also, in sitemap.rb, I added the lines:

include ActionController::UrlWriter
default_url_options[:host] = 'www.twoblindfish.com'

This allows you to use named routes and url_for. Now we don't need to hardcode our URLs! Another plus! The rest is pretty straight forward. A few of the tasks were redundant, so I refactored them into multiple functions for reuse.

The only thing really different would be to place your sitemaps in public/system/. so that the sitemaps don't get removed when you do a cap:deploy. This works because the public/system folder is symlinked to shared/system.

Hope this helps those in need of generating sitemaps!


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