Remove related_issues and add issue_links table

db/migrate/20170424131911_create_related_issues_table.rb

-class CreateRelatedIssuesTable < ActiveRecord::Migration
-  include Gitlab::Database::MigrationHelpers
-
-  DOWNTIME = false
-
-  disable_ddl_transaction!
-
-  def up
-    create_table :related_issues do |t|
-      t.integer :issue_id, null: false, index: true
-      t.integer :related_issue_id, null: false, index: true
-
-      t.timestamps null: true
-    end
-
-    add_index :related_issues, [:issue_id, :related_issue_id], unique: true
-
-    add_concurrent_foreign_key :related_issues, :issues, column: :issue_id
-    add_concurrent_foreign_key :related_issues, :issues, column: :related_issue_id
-  end
-
-  def down
-    drop_table :related_issues
-  end
-end

db/migrate/20170517162048_create_issue_links_table.rb

+class CreateIssueLinksTable < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    create_table :issue_links do |t|
+      t.integer :source_id, null: false, index: true
+      t.integer :target_id, null: false, index: true
+
+      t.timestamps null: true
+    end
+
+    add_index :issue_links, [:source_id, :target_id], unique: true
+
+    add_concurrent_foreign_key :issue_links, :issues, column: :source_id
+    add_concurrent_foreign_key :issue_links, :issues, column: :target_id
+  end
+
+  def down
+    drop_table :issue_links
+  end
+end

db/schema.rb

@@ -591,6 +591,17 @@ ActiveRecord::Schema.define(version: 20170602003304) do
   add_index "issue_assignees", ["issue_id", "user_id"], name: "index_issue_assignees_on_issue_id_and_user_id", unique: true, using: :btree
   add_index "issue_assignees", ["user_id"], name: "index_issue_assignees_on_user_id", using: :btree
 
+  create_table "issue_links", force: :cascade do |t|
+    t.integer "source_id", null: false
+    t.integer "target_id", null: false
+    t.datetime "created_at"
+    t.datetime "updated_at"
+  end
+
+  add_index "issue_links", ["source_id", "target_id"], name: "index_issue_links_on_source_id_and_target_id", unique: true, using: :btree
+  add_index "issue_links", ["source_id"], name: "index_issue_links_on_source_id", using: :btree
+  add_index "issue_links", ["target_id"], name: "index_issue_links_on_target_id", using: :btree
+
   create_table "issue_metrics", force: :cascade do |t|
     t.integer "issue_id", null: false
     t.datetime "first_mentioned_in_commit_at"
@@ -1304,17 +1315,6 @@ ActiveRecord::Schema.define(version: 20170602003304) do
   add_index "redirect_routes", ["path"], name: "index_redirect_routes_on_path_text_pattern_ops", using: :btree, opclasses: {"path"=>"varchar_pattern_ops"}
   add_index "redirect_routes", ["source_type", "source_id"], name: "index_redirect_routes_on_source_type_and_source_id", using: :btree
 
-  create_table "related_issues", force: :cascade do |t|
-    t.integer "issue_id", null: false
-    t.integer "related_issue_id", null: false
-    t.datetime "created_at"
-    t.datetime "updated_at"
-  end
-
-  add_index "related_issues", ["issue_id", "related_issue_id"], name: "index_related_issues_on_issue_id_and_related_issue_id", unique: true, using: :btree
-  add_index "related_issues", ["issue_id"], name: "index_related_issues_on_issue_id", using: :btree
-  add_index "related_issues", ["related_issue_id"], name: "index_related_issues_on_related_issue_id", using: :btree
-
   create_table "releases", force: :cascade do |t|
     t.string "tag"
     t.text "description"
@@ -1719,6 +1719,8 @@ ActiveRecord::Schema.define(version: 20170602003304) do
   add_foreign_key "container_repositories", "projects"
   add_foreign_key "issue_assignees", "issues", name: "fk_b7d881734a", on_delete: :cascade
   add_foreign_key "issue_assignees", "users", name: "fk_5e0c8d9154", on_delete: :cascade
+  add_foreign_key "issue_links", "issues", column: "source_id", name: "fk_c900194ff2", on_delete: :cascade
+  add_foreign_key "issue_links", "issues", column: "target_id", name: "fk_e71bb44f1f", on_delete: :cascade
   add_foreign_key "issue_metrics", "issues", on_delete: :cascade
   add_foreign_key "label_priorities", "labels", on_delete: :cascade
   add_foreign_key "label_priorities", "projects", on_delete: :cascade
@@ -1747,8 +1749,6 @@ ActiveRecord::Schema.define(version: 20170602003304) do
   add_foreign_key "protected_tag_create_access_levels", "namespaces", column: "group_id"
   add_foreign_key "protected_tag_create_access_levels", "protected_tags"
   add_foreign_key "protected_tag_create_access_levels", "users"
-  add_foreign_key "related_issues", "issues", column: "related_issue_id", name: "fk_f89e405611", on_delete: :cascade
-  add_foreign_key "related_issues", "issues", name: "fk_7bc934491d", on_delete: :cascade
   add_foreign_key "remote_mirrors", "projects"
   add_foreign_key "subscriptions", "projects", on_delete: :cascade
   add_foreign_key "system_note_metadata", "notes", name: "fk_d83a918cb1", on_delete: :cascade