Persist truncated note diffs on a new table45190-create-notes-diff-files

We request Gitaly in a N+1 manner to build discussion diffs. Once the diffs are from different revisions, it's hard to make a single request to the service in order to build the whole response.
With this change we solve this problem and simplify a lot fetching this piece of info.

1 files changed, 21 insertions, 0 deletions

diff --git a/db/migrate/20180515121227_create_notes_diff_files.rb b/db/migrate/20180515121227_create_notes_diff_files.rb
new file mode 100644
index 00000000000..7108bc1a64b
--- /dev/null
+++ b/db/migrate/20180515121227_create_notes_diff_files.rb
@@ -0,0 +1,21 @@
+class CreateNotesDiffFiles < ActiveRecord::Migration
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def change
+    create_table :note_diff_files do |t|
+      t.references :diff_note, references: :notes, null: false, index: { unique: true }
+      t.text :diff, null: false
+      t.boolean :new_file, null: false
+      t.boolean :renamed_file, null: false
+      t.boolean :deleted_file, null: false
+      t.string :a_mode, null: false
+      t.string :b_mode, null: false
+      t.text :new_path, null: false
+      t.text :old_path, null: false
+    end
+
+    add_foreign_key :note_diff_files, :notes, column: :diff_note_id, on_delete: :cascade
+  end
+end