Add/Remove Indexes - Metadata Table (#1128)

* Add missing index on metadata

* refactor the metadata queries

* fix rubocop issue

app/models/doi.rb

@@ -1867,7 +1867,7 @@ def to_jsonapi
   end
 
   def current_metadata
-    metadata.order("metadata.created DESC").first
+    metadata.first
   end
 
   def metadata_version

app/models/metadata.rb

@@ -61,7 +61,7 @@ def metadata_must_be_valid
 
   def set_metadata_version
     current_metadata =
-      Metadata.where(dataset: dataset).order("metadata.created DESC").first
+      Metadata.where(dataset: dataset).order("created DESC").first
     self.metadata_version =
       current_metadata.present? ? current_metadata.metadata_version + 1 : 0
   end

db/migrate/20240215091610_add_indexes_to_metadata.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class AddIndexesToMetadata < ActiveRecord::Migration[6.1]
+  def change
+    add_index :metadata, [:dataset, :created], name: "index_metadata_dataset_created"
+  end
+end

db/schema.rb

@@ -10,6 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
+
 ActiveRecord::Schema.define(version: 2024_02_29_195058) do
 
   create_table "active_storage_attachments", charset: "utf8mb4", force: :cascade do |t|
@@ -290,6 +291,7 @@
     t.bigint "dataset", null: false
     t.binary "is_converted_by_mds", limit: 1
     t.string "namespace"
+    t.index ["dataset", "created"], name: "index_metadata_dataset_created"
     t.index ["dataset", "metadata_version"], name: "dataset_version"
     t.index ["dataset"], name: "FKE52D7B2F4D3D6B1B"
   end