ActiveWarehouse

The ActiveWarehouse library provides classes and functions which help with building Data Warehouses using Rails. It can be installed either as a plugin or as a Gem.

To install as a plugin just use:

script/plugin install --force svn://rubyforge.org/var/svn/activewarehouse/activewarehouse/trunk

To get the latest edge version.

To install as a Gem, use:

gem install activewarehouse

On *nix you will need to run this command as root or better yet, using sudo.

Next, you will need to freeze or link the Gem to your Rails app. I prefer using the gemsonrails project:

gem install gemsonrails

And then in your Rails app:

rake gems:link GEM=activewarehouse

It is possible that freezing the Gem to the Rails app may not work at all times. It is most often best to install as a plugin.

Generators

ActiveWarehouse comes with several generators

script/generate fact Sales
script/generate fact sales

  Creates a SalesFact class and a sales_facts table.

script/generate dimension Region
script/generate dimension region

  Creates a RegionDimension class and a region_dimension table.

script/generate cube RegionalSales
script/generate cube regional_sales

  Creates a RegionalSalesCube class.

script/generate bridge CustomerHierarchy
script/generate bridge customer_hierarchy

  Creates a CustomerHierarchyBridge class.

script/generate dimension_view OrderDate Date
script/generate dimension_view order_date date

  Creates an OrderDateDimension class which is represented by a view on top
  of the DateDimension.

The rules for naming are as follows:

Facts:

Fact classes and tables follow the typical Rails rules: classes are singular
and tables are pluralized. 
Both the class and table name are suffixed by "_fact".

Dimensions:

Dimension classes and tables are both singular. 
Both the class name and the table name are suffixed by "_dimension".

Cube:

Cube class is singular. If a cube table is created it will also be singular.

Bridge:

Bridge classes and tables are both singular.
Both the class name and the table name are suffixed by "_bridge".

Dimension View:

Dimension View classes are singular. The underlying data structure is a view
on top of an existing dimension.
Both the class name and the view name are suffixed by "_dimension"

ETL

The ActiveWarehouse plugin does not directly handle Extract-Transform-Load processes, however the ActiveWarehouse ETL gem (installed separately) can help. To install it use:

gem install activewarehouse-etl

Once again you should run this command as root or using sudo.

More information on the ETL process can be found at activewarehouse.rubyforge.org/etl

Tutorial

A tutorial for ActiveWarehouse is available online at anthonyeden.com/2006/12/20/activewarehouse-example-with-rails-svn-logs (Note that is is out of date.)

You can also get a demo from the ActiveWarehouse subversion repository. Look in the SVN_ROOT/demo directory.