add index on stream_entries table (#5793)

db/migrate/20171129172043_add_index_on_stream_entries.rb

@@ -0,0 +1,7 @@
+class AddIndexOnStreamEntries < ActiveRecord::Migration[5.1]
+  def change
+    commit_db_transaction
+    add_index :stream_entries, [:account_id, :activity_type, :id], algorithm: :concurrently
+    remove_index :stream_entries, name: :index_stream_entries_on_account_id
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20171125190735) do
+ActiveRecord::Schema.define(version: 20171129172043) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -431,7 +431,7 @@ ActiveRecord::Schema.define(version: 20171125190735) do
     t.datetime "updated_at", null: false
     t.boolean "hidden", default: false, null: false
     t.bigint "account_id"
-    t.index ["account_id"], name: "index_stream_entries_on_account_id"
+    t.index ["account_id", "activity_type", "id"], name: "index_stream_entries_on_account_id_and_activity_type_and_id"
     t.index ["activity_id", "activity_type"], name: "index_stream_entries_on_activity_id_and_activity_type"
   end