New Features¶ ↑

• Dataset#for_no_key_update and for_key_share have been added on PostgreSQL. If you are not deleting a row or modifying a key column in a row, it is recommended to switch existing for_update calls to for_no_key_update, so they don’t take stronger locks than necessary (for_update will block concurrent INSERTs that reference a locked row).

• Check and foreign key constraints now support a :not_enforced option on PostgreSQL 18+, for using NOT ENFORCED. Constraints that are not enforced serve mostly documentation purposes, but they can be enforced later by altering the constraint.

• On PostgreSQL, alter_table blocks now support an alter_constraint method, which accepts the following options for altering the constraint:

  :deferrable	Modify deferrable setting for constraint (PostgreSQL 9.4+): true DEFERRABLE INITIALLY DEFERRED false NOT DEFERRABLE :immediate DEFERRABLE INITIALLY IMMEDIATE
  :enforced	Set true to use ENFORCED, or false to use NOT ENFORCED (PostgreSQL 18+)
  :inherit	Set true to use INHERIT, or false to use NO INHERIT (PostgreSQL 18+)

• Entries in Database#foreign_key_list, reverse_foreign_key_list, and check_constraint arrays on PostgreSQL now include :validated and :enforced entries to indicate whether the constraint is validated and enforced, respectively.

• :primary_key and :unique column options now support hash values in the schema generators. Using a hash value allows you to provide column constraint-specific options in the hash. This currently supports the :name and :deferrable options for both constraint types. Additional options will be supported in the future.

Other Improvements¶ ↑

• Dataset#for_share on PostgreSQL and MySQL now caches the returned dataset, similar to the caching done by for_update.

• Dataset#nolock on Microsoft SQL Server now caches the returned dataset, similar to the caching done by for_update.

• Many minor performance improvements have been applied, mostly fixed and/or flagged by rubocop-performance:

  • sort_by! instead of sort!

  • delete/tr instead of gsub

  • yield instead of block.call

  • start_with? accepts multiple arguments

  • Hash#[]= instead of merge!

  • Array.new instead of Integer#times.map

  • Hoist literal arrays inside loops to before the loop

  • Use block instead of Method#to_proc

  • Use start_with instead of regexp with A

  • Use String#include? instead of =~

• In the jdbc adapter, Database#foreign_key_list has been optimized, reducing the number of allocations.

• On DB2, multiple UNIQUE constraints on the same table are now handled when automatically marking columns as NOT NULL.