Improve db schema for merge request diffs

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

db/migrate/20140122112253_create_merge_request_diffs.rb

 class CreateMergeRequestDiffs < ActiveRecord::Migration
   def change
     create_table :merge_request_diffs do |t|
-      t.string :state, null: false, default: 'valid'
+      t.string :state, null: false, default: 'collected'
       t.text :st_commits, null: true, limit: 2147483647
       t.text :st_diffs, null: true, limit: 2147483647
       t.integer :merge_request_id, null: false

db/migrate/20140122122549_remove_m_rdiff_fields.rb

+class RemoveMRdiffFields < ActiveRecord::Migration
+  def up
+    remove_column :merge_requests, :st_commits
+    remove_column :merge_requests, :st_diffs
+  end
+
+  def down
+    add_column :merge_requests, :st_commits, :text, null: true, limit: 2147483647
+    add_column :merge_requests, :st_diffs, :text, null: true, limit: 2147483647
+    execute "UPDATE merge_requests mr, merge_request_diffs md SET mr.st_commits = md.st_commits WHERE md.merge_request_id = mr.id"
+    execute "UPDATE merge_requests mr, merge_request_diffs md SET mr.st_diffs = md.st_diffs WHERE md.merge_request_id = mr.id"
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20140122114406) do
+ActiveRecord::Schema.define(version: 20140122122549) do
 
   create_table "broadcast_messages", force: true do |t|
     t.text     "message",    null: false
@@ -96,7 +96,7 @@ ActiveRecord::Schema.define(version: 20140122114406) do
   add_index "keys", ["user_id"], name: "index_keys_on_user_id", using: :btree
 
   create_table "merge_request_diffs", force: true do |t|
-    t.string   "state",                               default: "valid", null: false
+    t.string   "state",                               default: "collected", null: false
     t.text     "st_commits",       limit: 2147483647
     t.text     "st_diffs",         limit: 2147483647
     t.integer  "merge_request_id",                                          null: false
@@ -113,8 +113,6 @@ ActiveRecord::Schema.define(version: 20140122114406) do
     t.string   "title"
     t.datetime "created_at"
     t.datetime "updated_at"
-    t.text     "st_commits",        limit: 2147483647
-    t.text     "st_diffs",          limit: 2147483647
     t.integer  "milestone_id"
     t.string   "state"
     t.string   "merge_status"