add initial migration file and further adjustments

The 01_setup.rb contains the old table structure to make it possible to
migrate to the new system.
02_move_to_new on the other hand adjusts the old schema to the new
format and adds the full text function.

With that, the new schema is ready and the completion of the full text
search can continue.

migrations/01_setup.rb

@@ -0,0 +1,47 @@
+Sequel.migration do
+  change do
+    create_table(:accounts) do
+      primary_key :id
+      String :username, :size=>50
+      String :email, :size=>50
+      String :crypted_password, :size=>70
+      String :role, :size=>50
+    end
+    
+    create_table(:tags) do
+      primary_key :id
+      String :name, :text=>true
+    end
+    
+    create_table(:posts, :ignore_index_errors=>true) do
+      primary_key :id
+      String :title, :text=>true, :null=>false
+      DateTime :written
+      TrueClass :released, :default=>false
+      String :markup, :default=>"markdown", :text=>true
+      String :content, :text=>true
+      foreign_key :account_id, :accounts, :null=>false, :key=>[:id]
+      
+      index [:account_id], :name=>:index_posts_account
+      index [:written, :id], :name=>:posts_written_id_idx
+    end
+    
+    create_table(:comments, :ignore_index_errors=>true) do
+      primary_key :id
+      String :author, :size=>50
+      String :email, :size=>50
+      TrueClass :acknowledged, :default=>false
+      String :body, :text=>true
+      foreign_key :post_id, :posts, :null=>false, :key=>[:id]
+      
+      index [:post_id], :name=>:index_comments_post
+    end
+    
+    create_table(:post_tags) do
+      foreign_key :post_id, :posts, :null=>false, :key=>[:id]
+      foreign_key :tag_id, :tags, :null=>false, :key=>[:id]
+      
+      primary_key [:post_id, :tag_id]
+    end
+  end
+end

migrations/02_move_to_new.rb

@@ -0,0 +1,52 @@
+# this is the schema from the old platform
+Sequel.migration do
+  up do
+    drop_table :post_tags
+    drop_table :comments
+    drop_table :tags
+
+    alter_table :posts  do
+      add_column :language, String, :size => 10
+    end
+
+    from(:posts).update(:language => 'english')
+
+    alter_table :posts do
+      set_column_not_null :language
+    end
+
+    run 'create function search_field(posts) returns tsvector as $$' +
+      "select to_tsvector($1.language::regconfig, $1.title || ' ' || $1.content);" +
+      '$$ language sql immutable;'
+  end
+
+  down do
+    alter_table :posts do
+      drop_column :language
+    end
+    run 'drop function search_field(posts);'
+
+    create_table(:tags) do
+      primary_key :id
+      String :name, :text=>true
+    end
+
+    create_table(:comments, :ignore_index_errors=>true) do
+      primary_key :id
+      String :author, :size=>50
+      String :email, :size=>50
+      TrueClass :acknowledged, :default=>false
+      String :body, :text=>true
+      foreign_key :post_id, :posts, :null=>false, :key=>[:id]
+      
+      index [:post_id], :name=>:index_comments_post
+    end
+    
+    create_table(:post_tags) do
+      foreign_key :post_id, :posts, :null=>false, :key=>[:id]
+      foreign_key :tag_id, :tags, :null=>false, :key=>[:id]
+      
+      primary_key [:post_id, :tag_id]
+    end
+  end
+end