New Features¶ ↑

• Database#{defer,immediate}_constraints methods have been added on PostgreSQL for changing handling of deferrable constraints inside a transaction. defer_constraints sets deferrable constraints to be deferred (not checked until transaction commit), and immediate_constraints sets deferrable constraints to be checked as part of the related query, and any already deferred constraint checks to be applied immediately. You can pass the :constraints option to only apply the changes to specific constraints.

• TimestampMigrator.run_single has been added, to migrate a single migration up or down.

Other Improvements¶ ↑

• INSERT RETURNING is now supported on MariaDB 10.5+, and used automatically when saving new model objects. Note that this is not supported when using the jdbc adapter, because the jdbc-mysql driver doesn’t support it. A jdbc/mariadb adapter could be added, as it’s likely recent versions of the jdbc-mariadb driver would support it, but the jdbc-mariadb gem hasn’t been updated in over 4 years. Talk to the jdbc-mariadb gem maintainers if you want to use this feature with the jdbc adapter.

• The Dataset#paged_each optimization in the postgres adapter now respects the :skip_transaction option, making it the same as the :hold option. Note that this has effects beyond just skipping the transaction, but non-HOLD cursors are only supported inside transactions.

• The any_not_empty? extension’s Dataset#any? method now supports an argument, passing it to Enumerable#any? (which has supported an argument since Ruby 2.5).