Enable query log tags by default on development env

This can be used to trace troublesome SQL statements back to the application code that generated these statements.

Author: MatheusRich

railties/CHANGELOG.md

@@ -1,3 +1,11 @@
+*   Enable query log tags by default on development env
+
+    This can be used to trace troublesome SQL statements back to the application
+    code that generated these statements. It is also useful when using multiple
+    databases because the query logs can identify which database is being used.
+
+    *Matheus Richard*
+
 *   Defer route drawing to the first request, or when url_helpers are called
 
     Executes the first routes reload in middleware, or when a route set's

railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt

@@ -59,6 +59,9 @@ Rails.application.configure do
   # Highlight code that triggered database queries in logs.
   config.active_record.verbose_query_logs = true
 
+  # Append comments with runtime information tags to SQL queries in logs.
+  config.active_record.query_log_tags_enabled = true
+
   <%- end -%>
   <%- unless options[:skip_active_job] -%>
   # Highlight code that enqueued background job in logs.

railties/test/application/configuration_test.rb

@@ -4737,6 +4737,14 @@ class Foo < ApplicationRecord
       assert_equal "SQLite", ActiveRecord::Base.lease_connection.adapter_name
     end
 
+    test "In development mode, config.active_record.query_log_tags_enabled is true by default" do
+      restore_default_config
+
+      app "development"
+
+      assert Rails.application.config.active_record.query_log_tags_enabled
+    end
+
     ["development", "production"].each do |env|
       test "active job adapter is async in #{env}" do
         app(env)