Ruby Hash#transform_keys now accepts a hash that maps existing keys to new keys
Ruby Hash#transform_keys now also accepts a hash that maps the existing hash keys to new keysRails has added strict loading mode to prevent lazy loading
Rails has added strict loading mode to prevent lazy loading of associations and help avoid N + 1 queriesRails adds config rake_eager_load
Rails has added the option to eager load all the registered name spaces in rake tasks.Rails has added support for automatic database connection switching from primary to the replica
Rails has added support for automatic database connection switching from primary to the replicaRuby 2.7 removes taint checking mechanism
Ruby 2.7 access and setting of $SAFE is now always warned. $SAFE will become a normal global variable in Ruby 3.0Rails 6.1 adds at option to perform_enqueued_jobs test helper
Rails 6.1 has added at option to perform_enqueued_jobs test helper to run only jobs which are scheduled at or before the passed in timeRails adds ActiveRecord API for switching multiple database connections
Rails adds ActiveRecord API connects_to and connected_to for switching connections to support multiple databases.Rails introduces disallowed deprecations in ActiveSupport
Rails has added support to configure disallowed deprecations.Rails has added a benchmark generator
Rails has added a benchmark generator for scripts to benchmark Rails application.Rails adds support for if_exists/if_not_exists on remove_column/add_column in migrations
Rails adds support for if_exists/if_not_exists on remove_column/add_column in migrations to silently ignore migrations