Hi,
I am new to this datawarehouse concept. I am trying to create a dw. I have
one dimension and one fact, namely: waste_dimension.rb, waste_fact.rb
Location of elt is db/elt
*My database.yml is something like:*
etl_execution:
adapter: mysql
database: rails_warehouse_etl_execution
username: root
password: password
host: localhost
warehouse:
adapter: mysql
database: for_demo
username: root
password: password
host: localhost
*I am using database for extract and load.*
*I am able to create a simple dimension table using following code:*
source :in, {
:database => "for_demo",
:target => :warehouse,
:table => "wastes",
:select => "wastes.name, wastes.type_id",
:order => "wastes.name"
},
[
:name,
:type_id
]
transform :name, :default, :default_value => "No Name"
destination :out, {
:database => "rails_warehouse_etl_execution",
:target => :etl_execution,
:table => 'waste_dimension'
},
{
:order => [
:name,
:type_id
]
}
Now I need to populate the watse_facts table. I am not sure how to go about
it. How do I add waste_id which is a foreign key from waste_dimesions table.
Also I wanted to add additional information from wastes table to waste_facts
table like co2e_factor (which I have not included in waste_dimensions table)
Structure for waste_dimension and waste_facts table is as follows:
class CreateWasteDimension < ActiveRecord::Migration
def self.up
fields = {
:name => :string,
:type_id => :integer
}
create_table :waste_dimension do |t|
fields.each do |name,type|
t.column name, type
end
end
fields.each do |name,type|
add_index :waste_dimension, name unless type == :text
end
end
def self.down
drop_table :waste_dimension
end
end
class CreateWasteFacts < ActiveRecord::Migration
def self.up
# you should add indexes for each foreign key, but don't add
# the foreign key itself unless you really know what you are doing.
create_table :waste_facts do |t|
t.column :waste_id, :integer, :null => false
t.column :co2e_factor, :integer, :default => 1
end
add_index :waste_facts, :waste_id
end
def self.down
drop_table :waste_facts
end
end
As I could not get any information on net hence mailing on this list. Please
help me resolve this problem. Thanks!
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