= New Features

* Dataset#merge and related #merge_* methods have been added for the
  MERGE statement.  MERGE is supported on PostgreSQL 15+, Oracle,
  Microsoft SQL Server, DB2, H2, HSQLDB, and Derby. You can use MERGE
  to insert, update, and/or delete in a single query.  You call
  the #merge_* methods to setup the MERGE statement, and #merge to
  execute it on the database:

    ds = DB[:m1]
      merge_using(:m2, i1: :i2).
      merge_insert(i1: :i2, a: Sequel[:b]+11).
      merge_delete{a > 30}.
      merge_update(i1: Sequel[:i1]+:i2+10, a: Sequel[:a]+:b+20)

    ds.merge
    # MERGE INTO m1 USING m2 ON (i1 = i2)
    # WHEN NOT MATCHED THEN INSERT (i1, a) VALUES (i2, (b + 11))
    # WHEN MATCHED AND (a > 30) THEN DELETE
    # WHEN MATCHED THEN UPDATE SET i1 = (i1 + i2 + 10), a = (a + b + 20)

  On PostgreSQL, the following additional MERGE related methods are
  available:

  * #merge_do_nothing_when_matched
  * #merge_do_nothing_when_not_matched

* A :disable_split_materialized Database option is now supported on
  MySQL. This disables split_materialized support in the optimizer,
  working around a bug in MariaDB 10.5+ that causes failures in
  Sequel's association tests.