Change column name to iid_per_project. Add index to project_id and iid

db/migrate/20180424160449_add_pipeline_iid_to_ci_pipelines.rb

@@ -6,10 +6,10 @@ class AddPipelineIidToCiPipelines < ActiveRecord::Migration
   disable_ddl_transaction!
 
   def up
-    add_column :ci_pipelines, :iid, :integer
+    add_column :ci_pipelines, :iid_per_project, :integer
   end
 
   def down
-    remove_column :ci_pipelines, :iid, :integer
+    remove_column :ci_pipelines, :iid_per_project, :integer
   end
 end

db/migrate/20180425205249_add_index_constraints_to_pipeline_iid.rb

+class AddIndexConstraintsToPipelineIid < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index :ci_pipelines, [:project_id, :iid_per_project], unique: true, where: 'iid_per_project IS NOT NULL'
+  end
+
+  def down
+    remove_concurrent_index :ci_pipelines, [:project_id, :iid_per_project]
+  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: 20180425131009) do
+ActiveRecord::Schema.define(version: 20180425205249) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -434,11 +434,12 @@ ActiveRecord::Schema.define(version: 20180425131009) do
     t.integer "config_source"
     t.boolean "protected"
     t.integer "failure_reason"
-    t.integer "iid"
+    t.integer "iid_per_project"
   end
 
   add_index "ci_pipelines", ["auto_canceled_by_id"], name: "index_ci_pipelines_on_auto_canceled_by_id", using: :btree
   add_index "ci_pipelines", ["pipeline_schedule_id"], name: "index_ci_pipelines_on_pipeline_schedule_id", using: :btree
+  add_index "ci_pipelines", ["project_id", "iid_per_project"], name: "index_ci_pipelines_on_project_id_and_iid_per_project", unique: true, where: "(iid_per_project IS NOT NULL)", using: :btree
   add_index "ci_pipelines", ["project_id", "ref", "status", "id"], name: "index_ci_pipelines_on_project_id_and_ref_and_status_and_id", using: :btree
   add_index "ci_pipelines", ["project_id", "sha"], name: "index_ci_pipelines_on_project_id_and_sha", using: :btree
   add_index "ci_pipelines", ["project_id"], name: "index_ci_pipelines_on_project_id", using: :btree