Add an index to improve the performance of issue queries involving custom fields (#29171).

Contributed by Stephane Evr.


git-svn-id: https://svn.redmine.org/redmine/trunk@21955 e93f8b46-1217-0410-a6f0-8f06a7374b81

db/migrate/20221012135202_add_index_to_custom_values.rb

@@ -0,0 +1,6 @@
+class AddIndexToCustomValues < ActiveRecord::Migration[6.1]
+  def change
+    remove_index :custom_values, column: [:customized_type, :customized_id], name: :custom_values_customized, if_exists: true
+    add_index :custom_values, [:customized_type, :customized_id, :custom_field_id], name: :custom_values_customized_custom_field
+  end
+end