Improve management of indexes and faux models in database migrations

24 files changed, 112 insertions, 37 deletions

diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/118_add_snapshots_qualifier_index.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/118_add_snapshots_qualifier_index.rb
index 1ee67cf96f1..aab8eeffda4 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/118_add_snapshots_qualifier_index.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/118_add_snapshots_qualifier_index.rb
@@ -24,7 +24,11 @@
 class AddSnapshotsQualifierIndex < ActiveRecord::Migration
 
   def self.up
-    add_index :snapshots, :qualifier, :name => 'snapshots_qualifier'
+    begin
+      add_index :snapshots, :qualifier, :name => 'snapshots_qualifier'
+    rescue
+      # already exists
+    end
   end
 
 end
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/119_add_measures_sid_metric_index.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/119_add_measures_sid_metric_index.rb
index 6387ea36c7d..cf8d6907908 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/119_add_measures_sid_metric_index.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/119_add_measures_sid_metric_index.rb
@@ -24,7 +24,11 @@
 class AddMeasuresSidMetricIndex < ActiveRecord::Migration
 
   def self.up
-    add_index :project_measures, [:snapshot_id, :metric_id], :name => 'measures_sid_metric'
+    begin
+      add_index :project_measures, [:snapshot_id, :metric_id], :name => 'measures_sid_metric'
+    rescue
+      # already exists
+    end
   end
 
 end
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/167_add_index_to_measure_data_snapshot.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/167_add_index_to_measure_data_snapshot.rb
index 0c858571c9c..fc83ebdfcc5 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/167_add_index_to_measure_data_snapshot.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/167_add_index_to_measure_data_snapshot.rb
@@ -24,7 +24,11 @@
 class AddIndexToMeasureDataSnapshot < ActiveRecord::Migration
 
   def self.up
-    add_index :measure_data, :snapshot_id, :name => 'm_data_sid'
+    begin
+      add_index :measure_data, :snapshot_id, :name => 'm_data_sid'
+    rescue
+      # already exists
+    end
   end
 
 end
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/190_add_permanent_id_and_switched_off_to_rule_failures.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/190_add_permanent_id_and_switched_off_to_rule_failures.rb
index 69ce668446a..be6f9ff3dd1 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/190_add_permanent_id_and_switched_off_to_rule_failures.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/190_add_permanent_id_and_switched_off_to_rule_failures.rb
@@ -26,9 +26,7 @@ class AddPermanentIdAndSwitchedOffToRuleFailures < ActiveRecord::Migration
   def self.up
     add_column 'rule_failures', 'permanent_id', :integer, :null => true
     add_column 'rule_failures', 'switched_off', :boolean, :null => true
-
     add_index 'rule_failures', 'permanent_id', :name => 'rf_permanent_id'
-    RuleFailure.reset_column_information
   end
 
 end
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/200_add_index_to_characteristic_property.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/200_add_index_to_characteristic_property.rb
index 6f45c9d9f71..e2868bd88e7 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/200_add_index_to_characteristic_property.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/200_add_index_to_characteristic_property.rb
@@ -24,7 +24,11 @@
 class AddIndexToCharacteristicProperty < ActiveRecord::Migration
 
   def self.up
-    add_index :characteristic_properties, :characteristic_id, :name => 'characteristic_properties_cid'
+    begin
+      add_index :characteristic_properties, :characteristic_id, :name => 'characteristic_properties_cid'
+    rescue
+      # already exists
+    end
   end
 
 end
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/201_change_false_positive_on_reviews.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/201_change_false_positive_on_reviews.rb
index 3bfae85db62..5e3a4b686f0 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/201_change_false_positive_on_reviews.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/201_change_false_positive_on_reviews.rb
@@ -23,14 +23,16 @@
 #
 class ChangeFalsePositiveOnReviews < ActiveRecord::Migration
 
+  class Review < ActiveRecord::Base
+  end
+
   def self.up
     add_column 'reviews', 'resolution', :string, :limit => 200, :null => true
-    Review.reset_column_information
 
+    Review.reset_column_information
     Review.update_all("status='RESOLVED', resolution='FALSE-POSITIVE'", "review_type='FALSE_POSITIVE'")
     
     remove_column 'reviews', 'review_type'
-    Review.reset_column_information
   end
 
 end
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/212_move_async_measures.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/212_move_async_measures.rb
index 17de99f74d6..dc720113b3d 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/212_move_async_measures.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/212_move_async_measures.rb
@@ -30,8 +30,10 @@ class MoveAsyncMeasures < ActiveRecord::Migration
   end
 
   def self.up
+    ProjectMeasure.reset_column_information
     deprecated_measures=ProjectMeasure.find_by_sql("select p1.* from project_measures p1 where p1.snapshot_id is null and p1.measure_date is not null and not exists(select id from project_measures p2 where p2.project_id=p1.project_id and p2.metric_id=p1.metric_id and p2.measure_date is not null and p2.measure_date>p1.measure_date)")
 
+    ManualMeasure.reset_column_information
     say_with_time "Moving #{deprecated_measures.size} measures" do
       deprecated_measures.each do |dm|
         if dm.project_id
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/214_add_index_on_manual_measures.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/214_add_index_on_manual_measures.rb
index c30fdd264b3..22dc78fa472 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/214_add_index_on_manual_measures.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/214_add_index_on_manual_measures.rb
@@ -24,7 +24,11 @@
 class AddIndexOnManualMeasures < ActiveRecord::Migration
 
   def self.up
-    add_index('manual_measures', 'resource_id', :name => 'manual_measures_resource_id')
+    begin
+      add_index 'manual_measures', 'resource_id', :name => 'manual_measures_resource_id'
+    rescue
+      # already exists
+    end
   end
 
 end
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/216_set_nullable_rule_name.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/216_set_nullable_rule_name.rb
index f1d7ed79184..0bd4490e049 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/216_set_nullable_rule_name.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/216_set_nullable_rule_name.rb
@@ -23,15 +23,17 @@
 #
 class SetNullableRuleName < ActiveRecord::Migration
 
+  class Rule < ActiveRecord::Base
+  end
+
   def self.up
     add_column(:rules, :temp_name, :string, :limit => 200, :null => true)
-    Rule.reset_column_information
 
+    Rule.reset_column_information
     Rule.update_all('temp_name=name')
 
     remove_column(:rules, :name)
     rename_column(:rules, :temp_name, :name)
-    Rule.reset_column_information
   end
 
 end
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/220_update_events_table.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/220_update_events_table.rb
index cc4d1e1b78b..5b9d623dcf3 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/220_update_events_table.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/220_update_events_table.rb
@@ -27,8 +27,6 @@ class UpdateEventsTable < ActiveRecord::Migration
     remove_column :events, :data
     change_column :events, :name, :string, :limit => 400, :null => true
     change_column :events, :description, :string, :limit => 4000, :null => true
-    
-    Event.reset_column_information
   end
 
 end
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/221_attach_events_to_snapshots.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/221_attach_events_to_snapshots.rb
index f0926a1a573..ff5f9dcb645 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/221_attach_events_to_snapshots.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/221_attach_events_to_snapshots.rb
@@ -22,9 +22,15 @@
 # Sonar 2.12
 #
 class AttachEventsToSnapshots < ActiveRecord::Migration
-  
+
+  class Event < ActiveRecord::Base
+  end
+
+
   def self.up
     logger = RAILS_DEFAULT_LOGGER
+    Event.reset_column_information
+
     Event.find(:all, :conditions => "snapshot_id IS NULL").each do |event|
       begin
         next_snapshot = Snapshot.find(:first, :conditions => ["created_at >= ? AND project_id = ?", event.event_date, event.resource_id], :order => :created_at)
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/231_refactor_rule_measures.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/231_refactor_rule_measures.rb
index 26a31dac2c9..191953072a4 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/231_refactor_rule_measures.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/231_refactor_rule_measures.rb
@@ -24,7 +24,16 @@
 #
 class RefactorRuleMeasures < ActiveRecord::Migration
 
+  class ProjectMeasure < ActiveRecord::Base
+  end
+
+  class Metric < ActiveRecord::Base
+  end
+
   def self.up
+    Metric.reset_column_information
+    ProjectMeasure.reset_column_information
+
     replace('violations', 0, 'info_violations')
     replace('violations', 1, 'minor_violations')
     replace('violations', 2, 'major_violations')
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/232_add_rule_columns_to_reviews.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/232_add_rule_columns_to_reviews.rb
index 6eb0114da10..1dc5d46040b 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/232_add_rule_columns_to_reviews.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/232_add_rule_columns_to_reviews.rb
@@ -26,7 +26,6 @@ class AddRuleColumnsToReviews < ActiveRecord::Migration
   def self.up
     add_column 'reviews', 'rule_id', :integer, :null => true
     add_column 'reviews', 'manual_violation', :boolean, :null => true
-    Review.reset_column_information
   end
 
 end
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/235_create_loaded_templates.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/235_create_loaded_templates.rb
index b4da00171a7..69c6dd45ca4 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/235_create_loaded_templates.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/235_create_loaded_templates.rb
@@ -23,6 +23,12 @@
 #
 class CreateLoadedTemplates < ActiveRecord::Migration
 
+  class Dashboard < ActiveRecord::Base
+  end
+
+  class LoadedTemplate < ActiveRecord::Base
+  end
+
   def self.up
     create_table 'loaded_templates' do |t|
       t.column 'kee', :string, :null => true, :limit => 200
@@ -30,8 +36,9 @@ class CreateLoadedTemplates < ActiveRecord::Migration
     end
 
     # if this is a migration, then the default dashboard already exists in the DB so it should not be loaded again
-    default_dashboard = Dashboard.find(:first, :conditions => {:name => 'Dashboard', :user_id => nil})
-    if default_dashboard
+    Dashboard.reset_column_information
+    if Dashboard.exists?(:name => 'Dashboard', :user_id => nil)
+      LoadedTemplate.reset_column_information
       LoadedTemplate.create({:template_type => 'DASHBOARD', :kee => 'Dashboard'})
     end
   end
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/236_delete_value_type_from_widget_properties.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/236_delete_value_type_from_widget_properties.rb
index 64361abfea5..fc6b91ed8c7 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/236_delete_value_type_from_widget_properties.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/236_delete_value_type_from_widget_properties.rb
@@ -25,7 +25,6 @@ class DeleteValueTypeFromWidgetProperties < ActiveRecord::Migration
 
   def self.up
     remove_column('widget_properties', 'value_type')
-    WidgetProperty.reset_column_information()
   end
 
 end
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/239_delete_duplications_id.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/239_delete_duplications_id.rb
index b7510faa0ae..47b2bd7ff42 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/239_delete_duplications_id.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/239_delete_duplications_id.rb
@@ -24,9 +24,7 @@
 class DeleteDuplicationsId < ActiveRecord::Migration
 
   def self.up
-    begin
-      remove_column('duplications_index', 'id')
-    end
+    remove_column('duplications_index', 'id')
   end
 
 end
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/240_delete_resource_orphans.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/240_delete_resource_orphans.rb
index 5c6d92a1bd4..42a4e89300a 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/240_delete_resource_orphans.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/240_delete_resource_orphans.rb
@@ -26,7 +26,11 @@
 #
 class DeleteResourceOrphans < ActiveRecord::Migration
 
+  class Project < ActiveRecord::Base
+  end
+
   def self.up
+    Project.reset_column_information
     ids=Project.find_by_sql(["select id from projects p where qualifier<>'LIB' and not exists (select * from snapshots s where s.project_id = p.id and s.islast=?)", true])
     say_with_time "Delete #{ids.size} resources" do
       # partition ids because of the Oracle limitation on IN statements
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/252_add_rule_and_active_rule_notes.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/252_add_rule_and_active_rule_notes.rb
index db934a2d24f..75ab8d5c467 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/252_add_rule_and_active_rule_notes.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/252_add_rule_and_active_rule_notes.rb
@@ -30,8 +30,7 @@ class AddRuleAndActiveRuleNotes < ActiveRecord::Migration
       t.column :user_login,         :string,      :null => true,    :limit => 40
       t.column :data,               :binary,      :null => true
     end
-    add_index :active_rule_notes, :active_rule_id
-    
+    add_index :active_rule_notes, :active_rule_id, :name => 'active_rule_notes_active_rule_id'
     
     create_table :rule_notes do |t|
       t.timestamps
@@ -39,7 +38,7 @@ class AddRuleAndActiveRuleNotes < ActiveRecord::Migration
       t.column :user_login,     :string,      :null => true,    :limit => 40
       t.column :data,           :binary,      :null => true
     end
-    add_index :rule_notes, :rule_id
+    add_index :rule_notes, :rule_id, :name => 'rule_notes_rule_id'
   end
 
 end
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/254_add_metrics_delete_historical_data.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/254_add_metrics_delete_historical_data.rb
index 41d8f665889..7794feae48f 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/254_add_metrics_delete_historical_data.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/254_add_metrics_delete_historical_data.rb
@@ -25,7 +25,6 @@ class AddMetricsDeleteHistoricalData < ActiveRecord::Migration
 
   def self.up
     add_column 'metrics', 'delete_historical_data', :boolean, :null => true
-    Metric.reset_column_information
   end
 
 end
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/255_rename_dbcleaner_properties.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/255_rename_dbcleaner_properties.rb
index c1b60665f4a..95338bd38f8 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/255_rename_dbcleaner_properties.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/255_rename_dbcleaner_properties.rb
@@ -28,6 +28,7 @@ class RenameDbcleanerProperties < ActiveRecord::Migration
 
 
   def self.up
+    Property.reset_column_information
     rename('sonar.dbcleaner.monthsBeforeKeepingOnlyOneSnapshotByWeek', 'sonar.dbcleaner.weeksBeforeKeepingOnlyOneSnapshotByWeek')
     rename('sonar.dbcleaner.monthsBeforeKeepingOnlyOneSnapshotByMonth', 'sonar.dbcleaner.weeksBeforeKeepingOnlyOneSnapshotByMonth')
     rename('sonar.dbcleaner.monthsBeforeDeletingAllSnapshots', 'sonar.dbcleaner.weeksBeforeDeletingAllSnapshots')
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/257_add_active_field_on_users.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/257_add_active_field_on_users.rb
index ddcb1b06d41..2a7da8f1afd 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/257_add_active_field_on_users.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/257_add_active_field_on_users.rb
@@ -23,10 +23,13 @@
 #
 class AddActiveFieldOnUsers < ActiveRecord::Migration
 
+  class User < ActiveRecord::Base
+  end
+
   def self.up
     add_column 'users', 'active', :boolean, :null => true, :default => true
+
     User.reset_column_information
-    
     User.find(:all).each do |user|
       user.active = true
       user.save
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/258_add_index_on_review_resource_id.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/258_add_index_on_review_resource_id.rb
index 40810ba2a7f..192777d5a63 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/258_add_index_on_review_resource_id.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/258_add_index_on_review_resource_id.rb
@@ -25,7 +25,7 @@ class AddIndexOnReviewResourceId < ActiveRecord::Migration
 
   def self.up
     begin
-      add_index('reviews', 'resource_id', :name => 'reviews_rid')
+      add_index('reviews', 'resource_id', :name => 'reviews_resource_id')
     rescue
       # already exists
     end
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/260_clean_reviews_with_deleted_users_or_resources.rb b/sonar-server/src/main/webapp/WEB-INF/db/migrate/260_clean_reviews_with_deleted_users_or_resources.rb
index b73a34f896b..68c5fc5b5dd 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/260_clean_reviews_with_deleted_users_or_resources.rb
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/260_clean_reviews_with_deleted_users_or_resources.rb
@@ -23,8 +23,14 @@
 #
 class CleanReviewsWithDeletedUsersOrResources < ActiveRecord::Migration
 
+  class Review < ActiveRecord::Base
+  end
+
+  class ReviewComment < ActiveRecord::Base
+  end
+
   def self.up
-    
+    Review.reset_column_information
     Review.find(:all, :include => ['resource', 'assignee', 'user']).each do |review|
       if review.resource_id && !review.resource
         # For http://jira.codehaus.org/browse/SONAR-3223
@@ -45,6 +51,7 @@ class CleanReviewsWithDeletedUsersOrResources < ActiveRecord::Migration
     end
 
     # For http://jira.codehaus.org/browse/SONAR-3102
+    ReviewComment.reset_column_information
     ReviewComment.find(:all, :include => 'user').each do |comment|
       comment.delete if comment.user_id && !comment.user
     end   
diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/README.txt b/sonar-server/src/main/webapp/WEB-INF/db/migrate/README.txt
index a5a7e8fcd91..1c3a2d850bb 100644
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/README.txt
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/README.txt
@@ -10,14 +10,36 @@ HOW TO ADD A MIGRATION
 
 
 
-RECOMMANDATIONS
+RECOMMENDATIONS
 
-* Don't forget that index name limited to 30 characters in Oracle DB.
 * Prefer to add nullable columns to avoid problems during migration.
-* When adding index, do not forget to name the index (so that it is possible later to delete it)
-  + Example: 
-      add_index "action_plans", "project_id", :name => "ap_project_id"
-* When modifying columns in a table, do not forget to reset the column information on the Ruby model if you use it 
-  + Example:
-      add_column 'users', 'active', :boolean, :null => true, :default => true
-      User.reset_column_information
+
+* Always create an index with a name : add_index "action_plans", "project_id", :name => "action_plans_project_id"
+  Note that this name is limited to 30 characters because of Oracle constraint.
+
+* Silently ignore failures when adding an index that has already been created by users. It can occur when the index
+  is not created in the same migration script than the table.
+
+  begin
+    add_index "action_plans", "project_id", :name => "action_plans_project_id"
+  rescue
+    # ignore
+  end
+
+* Use faux models when touching rows (SELECT/INSERT/UPDATE/DELETE). See http://guides.rubyonrails.org/migrations.html#using-models-in-your-migrations
+  for more details.
+
+  class MyMigration < ActiveRecord::Migration
+    # This is the faux model. It only maps columns. No functional methods.
+    class Metric < ActiveRecord::Base
+    end
+
+    def self.up
+      # it’s a good idea to call reset_column_information to refresh the ActiveRecord cache for the model prior to
+      # updating data in the database
+      Metric.reset_column_information
+      Metric.find(:all) do |m|
+        m.save
+      end
+    end
+  end
\ No newline at end of file