Add missing unique constraint to trending_projects.

2 files changed, 46 insertions, 3 deletions

diff --git a/db/migrate/20180131101040_add_unique_constraint_to_trending_projects_project_id.rb b/db/migrate/20180131101040_add_unique_constraint_to_trending_projects_project_id.rb
new file mode 100644
index 00000000000..a7a346743b9
--- /dev/null
+++ b/db/migrate/20180131101040_add_unique_constraint_to_trending_projects_project_id.rb
@@ -0,0 +1,43 @@
+class AddUniqueConstraintToTrendingProjectsProjectId < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  # Don't drop-and-create index so we don't have a gap
+  # Instead:
+  # 1) Add new index with temporary name
+  # 2) Drop old index
+  # 3) Rename new index back to original name
+
+  def up
+    add_concurrent_index :trending_projects, :project_id, unique: true, name: temp_index_name
+
+    remove_foreign_key :trending_projects, :projects
+    remove_concurrent_index :trending_projects, :project_id, name: actual_index_name
+    add_concurrent_foreign_key :trending_projects, :projects, column: :project_id, on_delete: :cascade
+
+    rename_index :trending_projects, temp_index_name, actual_index_name
+  end
+
+  def down
+    add_concurrent_index :trending_projects, :project_id, name: temp_index_name
+
+    remove_foreign_key :trending_projects, :projects
+    remove_concurrent_index :trending_projects, :project_id, name: actual_index_name
+    add_concurrent_foreign_key :trending_projects, :projects, column: :project_id, on_delete: :cascade
+
+    rename_index :trending_projects, temp_index_name, actual_index_name
+  end
+
+  private
+
+  def temp_index_name
+    'index_trending_projects_on_project_id_new'
+  end
+
+  def actual_index_name
+    'index_trending_projects_on_project_id'
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 4e82a688725..e7f0401031b 100644
--- a/db/schema.rb
+++ b/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: 20180115201419) do
+ActiveRecord::Schema.define(version: 20180131101040) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -1727,7 +1727,7 @@ ActiveRecord::Schema.define(version: 20180115201419) do
     t.integer "project_id", null: false
   end
 
-  add_index "trending_projects", ["project_id"], name: "index_trending_projects_on_project_id", using: :btree
+  add_index "trending_projects", ["project_id"], name: "index_trending_projects_on_project_id", unique: true, using: :btree
 
   create_table "u2f_registrations", force: :cascade do |t|
     t.text "certificate"
@@ -2038,7 +2038,7 @@ ActiveRecord::Schema.define(version: 20180115201419) do
   add_foreign_key "timelogs", "issues", name: "fk_timelogs_issues_issue_id", on_delete: :cascade
   add_foreign_key "timelogs", "merge_requests", name: "fk_timelogs_merge_requests_merge_request_id", on_delete: :cascade
   add_foreign_key "todos", "projects", name: "fk_45054f9c45", on_delete: :cascade
-  add_foreign_key "trending_projects", "projects", on_delete: :cascade
+  add_foreign_key "trending_projects", "projects", name: "fk_09feecd872", on_delete: :cascade
   add_foreign_key "u2f_registrations", "users"
   add_foreign_key "user_custom_attributes", "users", on_delete: :cascade
   add_foreign_key "user_synced_attributes_metadata", "users", on_delete: :cascade