Finish migration to the new events setup

This finishes the procedure for migrating events from the old format
into the new format. Code no longer uses the old setup and the database
tables used during the migration process are swapped, with the old table
being dropped.

While the database migration can be reversed this will 1) take a lot of
time as data has to be coped around 2) won't restore data in the
"events.data" column as we have no way of restoring this.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/37241

1 files changed, 48 insertions, 0 deletions

diff --git a/db/post_migrate/20170830150306_drop_events_for_migration_table.rb b/db/post_migrate/20170830150306_drop_events_for_migration_table.rb
new file mode 100644
index 00000000000..763ee9a810d
--- /dev/null
+++ b/db/post_migrate/20170830150306_drop_events_for_migration_table.rb
@@ -0,0 +1,48 @@
+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class DropEventsForMigrationTable < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  class Event < ActiveRecord::Base
+    include EachBatch
+  end
+
+  def up
+    transaction do
+      drop_table :events_for_migration
+    end
+  end
+
+  # rubocop: disable Migration/Datetime
+  def down
+    create_table :events_for_migration do |t|
+      t.string :target_type, index: true
+      t.integer :target_id, index: true
+      t.string :title
+      t.text :data
+      t.integer :project_id
+      t.datetime :created_at, index: true
+      t.datetime :updated_at
+      t.integer :action, index: true
+      t.integer :author_id, index: true
+
+      t.index [:project_id, :id]
+    end
+
+    Event.all.each_batch do |relation|
+      start_id, stop_id = relation.pluck('MIN(id), MAX(id)').first
+
+      execute <<-EOF.strip_heredoc
+      INSERT INTO events_for_migration (target_type, target_id, project_id, created_at, updated_at, action, author_id)
+      SELECT target_type, target_id, project_id, created_at, updated_at, action, author_id
+      FROM events
+      WHERE id BETWEEN #{start_id} AND #{stop_id}
+      EOF
+    end
+  end
+end