This is a major release that includes breaking changes. Please refer to the upgrade guide for more details.

API Improvements and Cleanup

• Strict scalar type declarations (#2854).
• Scalar parameter and return value types (#3511, #3569 and others).
• Disallow empty CompositeExpression #3868 and make it immutable #3858
• Improved error handling in prepared statements:
  • Transaction-related Statement methods return void and throw an exception
  • Converted Connection and Statement methods which returned false in case of a failure into void
• Improved behavior of Connection::getDatabase() (#3606)
• Autoincrement via identity columns on PostgreSQL
• Use native syntax for Top-N queries on Oracle (#5150) and IBM DB2 (#5156)
• Handle lost connection during commit #4713
• Reworked AbstractPlatform::get*Expression() methods #3498
• Do not require a WHERE in update() and delete() Connection operations #5567
• Improvements in exception hierarchy and semantics
• Remove defaults for MySQL table charset, collation and engine
• Convert ParameterType to enum
  • Convert enum-like classes to enums https://github.com/doctrine/dbal/pull/5554
• Improved Schema Diff API (no more public properties, almost immutable)

Major Backward Compatibility Breaks

• Get rid of hard-coded default values of maximum field lengths (#3586).
  • Column precision no longer defaults to 10. Scale and precision must be explicitly specified for decomal columns (#3348).
• Made the OFFSET in LIMIT queries non-nullable integer defaulting to 0
• Connection::quote() can only quote strings. Note that using this method is discouraged. Use prepared statements instead.
• Getting rid of the column name index #3583
• Represent table columns as list in the order of declaration #4777
• Drop support for SQL Server 2016 and older
• Drop support for Postgres 9
• Drop support for MySQL 5.6 and older and MariaDB 10.2.6 and older
• Drop support for MariaDB 10.4.2 and older
• Drop support for Oracle 12c and older
• Remove AbstractPlatform::hasNative*Type() methods and Type::requiresSQLCommentHint()
• Removed support for driver name aliases
• Removed extension via Doctrine Event Manager

Major Bugfixes

• Removed Connection::$_schemaManager() and ::getSchemaManager() (#4518)
• Removed Connection::$_expr (#4516) and ::getExpressionBuilder() (#4540)

Detailed Release Notes

• 4.0.0-RC2
• 4.0.0-RC1
• 4.0.0-beta3
• 4.0.0-beta2
• 4.0.0-beta1