Add index for user_id of pipeline

db/migrate/20160715134306_add_index_for_pipeline_user_id.rb

+class AddIndexForPipelineUserId < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  def change
+    add_index :ci_commits, :user_id
+  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: 20160715132507) do
+ActiveRecord::Schema.define(version: 20160715134306) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -211,6 +211,7 @@ ActiveRecord::Schema.define(version: 20160715132507) do
   add_index "ci_commits", ["project_id"], name: "index_ci_commits_on_project_id", using: :btree
   add_index "ci_commits", ["sha"], name: "index_ci_commits_on_sha", using: :btree
   add_index "ci_commits", ["status"], name: "index_ci_commits_on_status", using: :btree
+  add_index "ci_commits", ["user_id"], name: "index_ci_commits_on_user_id", using: :btree
 
   create_table "ci_events", force: :cascade do |t|
     t.integer  "project_id"