Add index to users lower login only for PostgreSQL and SQLite databases (#43838).

git-svn-id: https://svn.redmine.org/redmine/trunk@24518 e93f8b46-1217-0410-a6f0-8f06a7374b81

db/migrate/20260319062845_add_index_to_users_lower_login_on_postgres_and_sqlite.rb

@@ -0,0 +1,13 @@
+class AddIndexToUsersLowerLoginOnPostgresAndSqlite < ActiveRecord::Migration[8.1]
+  def up
+    if Redmine::Database.postgresql? || Redmine::Database.sqlite?
+      add_index :users, "(lower(login))", name: "index_users_on_lower_login"
+    end
+  end
+
+  def down
+    if index_exists?(:users, name: "index_users_on_lower_login")
+      remove_index :users, name: "index_users_on_lower_login"
+    end
+  end
+end