Add table for files in merge request diffs

This adds an ID-less table containing one row per file, per merge request
diff. It has a column for each attribute on Gitlab::Git::Diff that is serialised
currently, with the advantage that we can easily query the attributes of this
new table.

It does not migrate existing data, so we have fallback code when the legacy
st_diffs column is present instead. For a merge request diff to be valid, it
should have at most one of:

* Rows in this new table, with the correct merge_request_diff_id.
* A non-NULL st_diffs column.

It may have neither, if the diff is empty.

app/models/merge_request_diff.rb

@@ -10,6 +10,7 @@ class MergeRequestDiff < ActiveRecord::Base
   VALID_CLASSES = [Hash, Rugged::Patch, Rugged::Diff::Delta].freeze
   belongs_to :merge_request
+  has_many :merge_request_diff_files, -> { order(:merge_request_diff_id, :relative_order) }
   serialize :st_commits # rubocop:disable Cop/ActiverecordSerialize
   serialize :st_diffs # rubocop:disable Cop/ActiverecordSerialize
@@ -91,7 +92,7 @@ class MergeRequestDiff < ActiveRecord::Base
           head_commit_sha).diffs(options)
     else
       @raw_diffs ||= {}
-      @raw_diffs[options] ||= load_diffs(st_diffs, options)
+      @raw_diffs[options] ||= load_diffs(options)
     end
   end
@@ -253,24 +254,44 @@ class MergeRequestDiff < ActiveRecord::Base
     update_columns_serialized(new_attributes)
   end
-  def dump_diffs(diffs)
-    if diffs.respond_to?(:map)
-      diffs.map(&:to_hash)
+  def create_merge_request_diff_files(diffs)
+    rows = diffs.map.with_index do |diff, index|
+      diff.to_hash.merge(
+        merge_request_diff_id: self.id,
+        relative_order: index
+      )
     end
+
+    Gitlab::Database.bulk_insert('merge_request_diff_files', rows)
   end
-  def load_diffs(raw, options)
-    if valid_raw_diff?(raw)
-      if paths = options[:paths]
-        raw = raw.select do |diff|
-          paths.include?(diff[:old_path]) || paths.include?(diff[:new_path])
-        end
-      end
-      Gitlab::Git::DiffCollection.new(raw, options)
-    else
-      Gitlab::Git::DiffCollection.new([])
+  def load_diffs(options)
+    return Gitlab::Git::DiffCollection.new([]) unless diffs_from_database
+    raw = diffs_from_database
+
+    if paths = options[:paths]
+      raw = raw.select do |diff|
+        paths.include?(diff[:old_path]) || paths.include?(diff[:new_path])
+      end
     end
+
+    Gitlab::Git::DiffCollection.new(raw, options)
+  end
+
+  def diffs_from_database
+    return @diffs_from_database if defined?(@diffs_from_database)
+
+    @diffs_from_database =
+      if st_diffs.present?
+        if valid_raw_diff?(st_diffs)
+          st_diffs
+        end
+      elsif merge_request_diff_files.present?
+        merge_request_diff_files
+          .as_json(only: Gitlab::Git::Diff::SERIALIZE_KEYS)
+          .map(&:with_indifferent_access)
+      end
   end
   # Load diffs between branches related to current merge request diff from repo
@@ -285,11 +306,10 @@ class MergeRequestDiff < ActiveRecord::Base
       new_attributes[:real_size] = diff_collection.real_size
       if diff_collection.any?
-        new_diffs = dump_diffs(diff_collection)
         new_attributes[:state] = :collected
-      end
-      new_attributes[:st_diffs] = new_diffs || []
+        create_merge_request_diff_files(diff_collection)
+      end
       # Set our state to 'overflow' to make the #empty? and #collected?
       # methods (generated by StateMachine) return false.

app/models/merge_request_diff_file.rb

+class MergeRequestDiffFile < ActiveRecord::Base
+  include Gitlab::EncodingHelper
+
+  belongs_to :merge_request_diff
+
+  def utf8_diff
+    return '' if diff.blank?
+
+    encode_utf8(diff) if diff.respond_to?(:encoding)
+  end
+end

db/migrate/20170608171156_create_merge_request_diff_files.rb

+class CreateMergeRequestDiffFiles < ActiveRecord::Migration
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def change
+    create_table :merge_request_diff_files, id: false do |t|
+      t.belongs_to :merge_request_diff, null: false, foreign_key: { on_delete: :cascade }
+      t.integer :relative_order, null: false
+      t.boolean :new_file, null: false
+      t.boolean :renamed_file, null: false
+      t.boolean :deleted_file, null: false
+      t.boolean :too_large, 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
+      t.text :diff, null: false
+      t.index [:merge_request_diff_id, :relative_order], name: 'index_merge_request_diff_files_on_mr_diff_id_and_order', unique: true
+    end
+  end
+end

db/migrate/20170614115405_merge_request_diff_file_limits_to_mysql.rb

+require_relative 'merge_request_diff_file_limits_to_mysql'

db/migrate/merge_request_diff_file_limits_to_mysql.rb

+class MergeRequestDiffFileLimitsToMysql < ActiveRecord::Migration
+  DOWNTIME = false
+
+  def up
+    return unless Gitlab::Database.mysql?
+
+    change_column :merge_request_diff_files, :diff, :text, limit: 2147483647
+  end
+
+  def down
+  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: 20170609183112) do
+ActiveRecord::Schema.define(version: 20170614115405) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -692,6 +692,22 @@ ActiveRecord::Schema.define(version: 20170609183112) do
   add_index "members", ["source_id", "source_type"], name: "index_members_on_source_id_and_source_type", using: :btree
   add_index "members", ["user_id"], name: "index_members_on_user_id", using: :btree
+  create_table "merge_request_diff_files", id: false, force: :cascade do |t|
+    t.integer "merge_request_diff_id", null: false
+    t.integer "relative_order", null: false
+    t.boolean "new_file", null: false
+    t.boolean "renamed_file", null: false
+    t.boolean "deleted_file", null: false
+    t.boolean "too_large", 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
+    t.text "diff", null: false
+  end
+
+  add_index "merge_request_diff_files", ["merge_request_diff_id", "relative_order"], name: "index_merge_request_diff_files_on_mr_diff_id_and_order", unique: true, using: :btree
+
   create_table "merge_request_diffs", force: :cascade do |t|
     t.string "state"
     t.text "st_commits"
@@ -1530,6 +1546,7 @@ ActiveRecord::Schema.define(version: 20170609183112) do
   add_foreign_key "labels", "namespaces", column: "group_id", on_delete: :cascade
   add_foreign_key "lists", "boards"
   add_foreign_key "lists", "labels"
+  add_foreign_key "merge_request_diff_files", "merge_request_diffs", on_delete: :cascade
   add_foreign_key "merge_request_metrics", "ci_pipelines", column: "pipeline_id", on_delete: :cascade
   add_foreign_key "merge_request_metrics", "merge_requests", on_delete: :cascade
   add_foreign_key "merge_requests_closing_issues", "issues", on_delete: :cascade

doc/user/project/settings/import_export.md

@@ -27,14 +27,15 @@ with all their related data and be moved into a new GitLab instance.
 | GitLab version | Import/Export version |
 | -------- | -------- |
-| 9.2.0 to current | 0.1.7 |
-| 8.17.0   | 0.1.6    |
-| 8.13.0   | 0.1.5    |
-| 8.12.0   | 0.1.4    |
-| 8.10.3   | 0.1.3    |
-| 8.10.0   | 0.1.2    |
-| 8.9.5    | 0.1.1    |
-| 8.9.0    | 0.1.0    |
+| 9.4.0 to current | 0.1.8 |
+| 9.2.0    | 0.1.7 |
+| 8.17.0   | 0.1.6 |
+| 8.13.0   | 0.1.5 |
+| 8.12.0   | 0.1.4 |
+| 8.10.3   | 0.1.3 |
+| 8.10.0   | 0.1.2 |
+| 8.9.5    | 0.1.1 |
+| 8.9.0    | 0.1.0 |
  > The table reflects what GitLab version we updated the Import/Export version at.
  > For instance, 8.10.3 and 8.11 will have the same Import/Export version (0.1.3)

lib/gitlab/database.rb

@@ -83,6 +83,22 @@ module Gitlab
       end
     end
+    def self.bulk_insert(table, rows)
+      return if rows.empty?
+
+      keys = rows.first.keys
+      columns = keys.map { |key| connection.quote_column_name(key) }
+
+      tuples = rows.map do |row|
+        row.values_at(*keys).map { |value| connection.quote(value) }
+      end
+
+      connection.execute <<-EOF.strip_heredoc
+        INSERT INTO #{table} (#{columns.join(', ')})
+        VALUES #{tuples.map { |tuple| "(#{tuple.join(', ')})" }.join(', ')}
+      EOF
+    end
+
     # pool_size - The size of the DB pool.
     # host - An optional host name to use instead of the default one.
     def self.create_connection_pool(pool_size, host = nil)

lib/gitlab/git/diff.rb

@@ -16,11 +16,11 @@ module Gitlab
       alias_method :renamed_file?, :renamed_file
       attr_accessor :expanded
+      attr_writer :too_large
       alias_method :expanded?, :expanded
-      # We need this accessor because of `to_hash` and `init_from_hash`
-      attr_accessor :too_large
+      SERIALIZE_KEYS = %i(diff new_path old_path a_mode b_mode new_file renamed_file deleted_file too_large).freeze
       class << self
         # The maximum size of a diff to display.
@@ -231,16 +231,10 @@ module Gitlab
         end
       end
-      def serialize_keys
-        @serialize_keys ||= %i(diff new_path old_path a_mode b_mode new_file renamed_file deleted_file too_large)
-      end
-
       def to_hash
         hash = {}
-        keys = serialize_keys
-
-        keys.each do |key|
+        SERIALIZE_KEYS.each do |key|
           hash[key] = send(key)
         end
@@ -267,6 +261,9 @@ module Gitlab
         end
       end
+      # This is used by `to_hash` and `init_from_hash`.
+      alias_method :too_large, :too_large?
+
       def too_large!
         @diff = ''
         @line_count = 0
@@ -315,7 +312,7 @@ module Gitlab
       def init_from_hash(hash)
         raw_diff = hash.symbolize_keys
-        serialize_keys.each do |key|
+        SERIALIZE_KEYS.each do |key|
           send(:"#{key}=", raw_diff[key.to_sym])
         end
       end

lib/gitlab/import_export.rb

@@ -3,7 +3,7 @@ module Gitlab
     extend self
     # For every version update, the version history in import_export.md has to be kept up to date.
-    VERSION = '0.1.7'.freeze
+    VERSION = '0.1.8'.freeze
     FILENAME_LIMIT = 50
     def export_path(relative_path:)

lib/gitlab/import_export/import_export.yml

@@ -26,7 +26,8 @@ project_tree:
     - notes:
       - :author
       - :events
-    - :merge_request_diff
+    - merge_request_diff:
+      - :merge_request_diff_files
     - :events
     - :timelogs
     - label_links:
@@ -92,6 +93,8 @@ excluded_attributes:
     - :expired_at
   merge_request_diff:
     - :st_diffs
+  merge_request_diff_files:
+    - :diff
   issues:
     - :milestone_id
   merge_requests:
@@ -113,6 +116,8 @@ methods:
     - :type
   merge_request_diff:
     - :utf8_st_diffs
+  merge_request_diff_files:
+    - :utf8_diff
   merge_requests:
     - :diff_head_sha
   project:

lib/gitlab/import_export/json_hash_builder.rb

@@ -83,7 +83,9 @@ module Gitlab
       # +value+ existing model to be included in the hash
       # +json_config_hash+ the original hash containing the root model
       def add_model_value(current_key, value, json_config_hash)
-        @attributes_finder.parse(value) { |hash| value = { value => hash } }
+        @attributes_finder.parse(value) do |hash|
+          value = { value => hash } unless value.is_a?(Hash)
+        end
         add_to_array(current_key, json_config_hash, value)
       end

lib/gitlab/import_export/relation_factory.rb

@@ -71,6 +71,7 @@ module Gitlab
         @relation_hash['data'].deep_symbolize_keys! if @relation_name == :events && @relation_hash['data']
         set_st_diff_commits if @relation_name == :merge_request_diff
+        set_diff if @relation_name == :merge_request_diff_files
       end
       def update_user_references
@@ -202,6 +203,10 @@ module Gitlab
         HashUtil.deep_symbolize_array_with_date!(@relation_hash['st_commits'])
       end
+      def set_diff
+        @relation_hash['diff'] = @relation_hash.delete('utf8_diff')
+      end
+
       def existing_or_new_object
         # Only find existing records to avoid mapping tables such as milestones
         # Otherwise always create the record, skipping the extra SELECT clause.

lib/tasks/migrate/add_limits_mysql.rake

 require Rails.root.join('db/migrate/limits_to_mysql')
 require Rails.root.join('db/migrate/markdown_cache_limits_to_mysql')
+require Rails.root.join('db/migrate/merge_request_diff_file_limits_to_mysql')
 desc "GitLab | Add limits to strings in mysql database"
 task add_limits_mysql: :environment do
   puts "Adding limits to schema.rb for mysql"
   LimitsToMysql.new.up
   MarkdownCacheLimitsToMysql.new.up
+  MergeRequestDiffFileLimitsToMysql.new.up
 end

spec/lib/gitlab/database_spec.rb

@@ -129,6 +129,55 @@ describe Gitlab::Database, lib: true do
     end
   end
+  describe '.bulk_insert' do
+    before do
+      allow(described_class).to receive(:connection).and_return(connection)
+      allow(connection).to receive(:quote_column_name, &:itself)
+      allow(connection).to receive(:quote, &:itself)
+      allow(connection).to receive(:execute)
+    end
+
+    let(:connection) { double(:connection) }
+
+    let(:rows) do
+      [
+        { a: 1, b: 2, c: 3 },
+        { c: 6, a: 4, b: 5 }
+      ]
+    end
+
+    it 'does nothing with empty rows' do
+      expect(connection).not_to receive(:execute)
+
+      described_class.bulk_insert('test', [])
+    end
+
+    it 'uses the ordering from the first row' do
+      expect(connection).to receive(:execute) do |sql|
+        expect(sql).to include('(1, 2, 3)')
+        expect(sql).to include('(4, 5, 6)')
+      end
+
+      described_class.bulk_insert('test', rows)
+    end
+
+    it 'quotes column names' do
+      expect(connection).to receive(:quote_column_name).with(:a)
+      expect(connection).to receive(:quote_column_name).with(:b)
+      expect(connection).to receive(:quote_column_name).with(:c)
+
+      described_class.bulk_insert('test', rows)
+    end
+
+    it 'quotes values' do
+      1.upto(6) do |i|
+        expect(connection).to receive(:quote).with(i)
+      end
+
+      described_class.bulk_insert('test', rows)
+    end
+  end
+
   describe '.create_connection_pool' do
     it 'creates a new connection pool with specific pool size' do
       pool = described_class.create_connection_pool(5)

spec/lib/gitlab/git/diff_spec.rb

@@ -90,7 +90,7 @@ EOT
         let(:diff) { described_class.new(@rugged_diff) }
         it 'initializes the diff' do
-          expect(diff.to_hash).to eq(@raw_diff_hash.merge(too_large: nil))
+          expect(diff.to_hash).to eq(@raw_diff_hash)
         end
         it 'does not prune the diff' do

spec/lib/gitlab/import_export/all_models.yml

@@ -88,6 +88,9 @@ merge_requests:
 - head_pipeline
 merge_request_diff:
 - merge_request
+- merge_request_diff_files
+merge_request_diff_files:
+- merge_request_diff
 pipelines:
 - project
 - user

spec/lib/gitlab/import_export/project.json

@@ -2821,9 +2821,11 @@
             "committer_email": "dmitriy.zaporozhets@gmail.com"
           }
         ],
-        "utf8_st_diffs": [
+        "merge_request_diff_files": [
           {
-            "diff": "Binary files a/.DS_Store and /dev/null differ\n",
+            "merge_request_diff_id": 27,
+            "relative_order": 0,
+            "utf8_diff": "Binary files a/.DS_Store and /dev/null differ\n",
             "new_path": ".DS_Store",
             "old_path": ".DS_Store",
             "a_mode": "100644",
@@ -2834,7 +2836,9 @@
             "too_large": false
           },
           {
-            "diff": "--- a/.gitignore\n+++ b/.gitignore\n@@ -17,3 +17,4 @@ rerun.txt\n pickle-email-*.html\n .project\n config/initializers/secret_token.rb\n+.DS_Store\n",
+            "merge_request_diff_id": 27,
+            "relative_order": 1,
+            "utf8_diff": "--- a/.gitignore\n+++ b/.gitignore\n@@ -17,3 +17,4 @@ rerun.txt\n pickle-email-*.html\n .project\n config/initializers/secret_token.rb\n+.DS_Store\n",
             "new_path": ".gitignore",
             "old_path": ".gitignore",
             "a_mode": "100644",
@@ -2845,7 +2849,9 @@
             "too_large": false
           },
           {
-            "diff": "--- a/.gitmodules\n+++ b/.gitmodules\n@@ -1,3 +1,9 @@\n [submodule \"six\"]\n \tpath = six\n \turl = git://github.com/randx/six.git\n+[submodule \"gitlab-shell\"]\n+\tpath = gitlab-shell\n+\turl = https://github.com/gitlabhq/gitlab-shell.git\n+[submodule \"gitlab-grack\"]\n+\tpath = gitlab-grack\n+\turl = https://gitlab.com/gitlab-org/gitlab-grack.git\n",
+            "merge_request_diff_id": 27,
+            "relative_order": 2,
+            "utf8_diff": "--- a/.gitmodules\n+++ b/.gitmodules\n@@ -1,3 +1,9 @@\n [submodule \"six\"]\n \tpath = six\n \turl = git://github.com/randx/six.git\n+[submodule \"gitlab-shell\"]\n+\tpath = gitlab-shell\n+\turl = https://github.com/gitlabhq/gitlab-shell.git\n+[submodule \"gitlab-grack\"]\n+\tpath = gitlab-grack\n+\turl = https://gitlab.com/gitlab-org/gitlab-grack.git\n",
             "new_path": ".gitmodules",
             "old_path": ".gitmodules",
             "a_mode": "100644",
@@ -2856,7 +2862,9 @@
             "too_large": false
           },
           {
-            "diff": "Binary files a/files/.DS_Store and /dev/null differ\n",
+            "merge_request_diff_id": 27,
+            "relative_order": 3,
+            "utf8_diff": "Binary files a/files/.DS_Store and /dev/null differ\n",
             "new_path": "files/.DS_Store",
             "old_path": "files/.DS_Store",
             "a_mode": "100644",
@@ -2867,7 +2875,9 @@
             "too_large": false
           },
           {
-            "diff": "--- /dev/null\n+++ b/files/ruby/feature.rb\n@@ -0,0 +1,4 @@\n+# This file was changed in feature branch\n+# We put different code here to make merge conflict\n+class Conflict\n+end\n",
+            "merge_request_diff_id": 27,
+            "relative_order": 4,
+            "utf8_diff": "--- /dev/null\n+++ b/files/ruby/feature.rb\n@@ -0,0 +1,4 @@\n+# This file was changed in feature branch\n+# We put different code here to make merge conflict\n+class Conflict\n+end\n",
             "new_path": "files/ruby/feature.rb",
             "old_path": "files/ruby/feature.rb",
             "a_mode": "0",
@@ -2878,7 +2888,9 @@
             "too_large": false
           },
           {
-            "diff": "--- a/files/ruby/popen.rb\n+++ b/files/ruby/popen.rb\n@@ -6,12 +6,18 @@ module Popen\n \n   def popen(cmd, path=nil)\n     unless cmd.is_a?(Array)\n-      raise \"System commands must be given as an array of strings\"\n+      raise RuntimeError, \"System commands must be given as an array of strings\"\n     end\n \n     path ||= Dir.pwd\n-    vars = { \"PWD\" =\u003e path }\n-    options = { chdir: path }\n+\n+    vars = {\n+      \"PWD\" =\u003e path\n+    }\n+\n+    options = {\n+      chdir: path\n+    }\n \n     unless File.directory?(path)\n       FileUtils.mkdir_p(path)\n@@ -19,6 +25,7 @@ module Popen\n \n     @cmd_output = \"\"\n     @cmd_status = 0\n+\n     Open3.popen3(vars, *cmd, options) do |stdin, stdout, stderr, wait_thr|\n       @cmd_output \u003c\u003c stdout.read\n       @cmd_output \u003c\u003c stderr.read\n",
+            "merge_request_diff_id": 27,
+            "relative_order": 5,
+            "utf8_diff": "--- a/files/ruby/popen.rb\n+++ b/files/ruby/popen.rb\n@@ -6,12 +6,18 @@ module Popen\n \n   def popen(cmd, path=nil)\n     unless cmd.is_a?(Array)\n-      raise \"System commands must be given as an array of strings\"\n+      raise RuntimeError, \"System commands must be given as an array of strings\"\n     end\n \n     path ||= Dir.pwd\n-    vars = { \"PWD\" =\u003e path }\n-    options = { chdir: path }\n+\n+    vars = {\n+      \"PWD\" =\u003e path\n+    }\n+\n+    options = {\n+      chdir: path\n+    }\n \n     unless File.directory?(path)\n       FileUtils.mkdir_p(path)\n@@ -19,6 +25,7 @@ module Popen\n \n     @cmd_output = \"\"\n     @cmd_status = 0\n+\n     Open3.popen3(vars, *cmd, options) do |stdin, stdout, stderr, wait_thr|\n       @cmd_output \u003c\u003c stdout.read\n       @cmd_output \u003c\u003c stderr.read\n",
             "new_path": "files/ruby/popen.rb",
             "old_path": "files/ruby/popen.rb",
             "a_mode": "100644",
@@ -2889,7 +2901,9 @@
             "too_large": false
           },
           {
-            "diff": "--- a/files/ruby/regex.rb\n+++ b/files/ruby/regex.rb\n@@ -19,14 +19,12 @@ module Gitlab\n     end\n \n     def archive_formats_regex\n-      #|zip|tar|    tar.gz    |         tar.bz2         |\n-      /(zip|tar|tar\\.gz|tgz|gz|tar\\.bz2|tbz|tbz2|tb2|bz2)/\n+      /(zip|tar|7z|tar\\.gz|tgz|gz|tar\\.bz2|tbz|tbz2|tb2|bz2)/\n     end\n \n     def git_reference_regex\n       # Valid git ref regex, see:\n       # https://www.kernel.org/pub/software/scm/git/docs/git-check-ref-format.html\n-\n       %r{\n         (?!\n            (?# doesn't begins with)\n",
+            "merge_request_diff_id": 27,
+            "relative_order": 6,
+            "utf8_diff": "--- a/files/ruby/regex.rb\n+++ b/files/ruby/regex.rb\n@@ -19,14 +19,12 @@ module Gitlab\n     end\n \n     def archive_formats_regex\n-      #|zip|tar|    tar.gz    |         tar.bz2         |\n-      /(zip|tar|tar\\.gz|tgz|gz|tar\\.bz2|tbz|tbz2|tb2|bz2)/\n+      /(zip|tar|7z|tar\\.gz|tgz|gz|tar\\.bz2|tbz|tbz2|tb2|bz2)/\n     end\n \n     def git_reference_regex\n       # Valid git ref regex, see:\n       # https://www.kernel.org/pub/software/scm/git/docs/git-check-ref-format.html\n-\n       %r{\n         (?!\n            (?# doesn't begins with)\n",
             "new_path": "files/ruby/regex.rb",
             "old_path": "files/ruby/regex.rb",
             "a_mode": "100644",
@@ -2900,7 +2914,9 @@
             "too_large": false
           },
           {
-            "diff": "--- /dev/null\n+++ b/gitlab-grack\n@@ -0,0 +1 @@\n+Subproject commit 645f6c4c82fd3f5e06f67134450a570b795e55a6\n",
+            "merge_request_diff_id": 27,
+            "relative_order": 7,
+            "utf8_diff": "--- /dev/null\n+++ b/gitlab-grack\n@@ -0,0 +1 @@\n+Subproject commit 645f6c4c82fd3f5e06f67134450a570b795e55a6\n",
             "new_path": "gitlab-grack",
             "old_path": "gitlab-grack",
             "a_mode": "0",
@@ -2911,7 +2927,9 @@
             "too_large": false
           },
           {
-            "diff": "--- /dev/null\n+++ b/gitlab-shell\n@@ -0,0 +1 @@\n+Subproject commit 79bceae69cb5750d6567b223597999bfa91cb3b9\n",
+            "merge_request_diff_id": 27,
+            "relative_order": 8,
+            "utf8_diff": "--- /dev/null\n+++ b/gitlab-shell\n@@ -0,0 +1 @@\n+Subproject commit 79bceae69cb5750d6567b223597999bfa91cb3b9\n",
             "new_path": "gitlab-shell",
             "old_path": "gitlab-shell",
             "a_mode": "0",

spec/lib/gitlab/import_export/project_tree_restorer_spec.rb

@@ -86,8 +86,13 @@ describe Gitlab::ImportExport::ProjectTreeRestorer, services: true do
       it 'has the correct data for merge request st_diffs' do
         # makes sure we are renaming the custom method +utf8_st_diffs+ into +st_diffs+
-        expect(MergeRequestDiff.where.not(st_diffs: nil).count).to eq(9)
+        # one MergeRequestDiff uses the new format, where st_diffs is expected to be nil
+        expect(MergeRequestDiff.where.not(st_diffs: nil).count).to eq(8)
+      end
+
+      it 'has the correct data for merge request diff files' do
+        expect(MergeRequestDiffFile.where.not(diff: nil).count).to eq(9)
       end
       it 'has the correct time for merge request st_commits' do