Sequel 2.5

Major Features:

1. Sequel provides thread safety, connection pooling and a concise DSL for constructing database queries and table schemas.
2. Sequel also includes a lightweight but comprehensive ORM layer for mapping records to Ruby objects and handling associated records.
3. Sequel supports advanced database features such as prepared statements, bound variables, stored procedures, master/slave configurations, and database sharding.
4. Sequel makes it easy to deal with multiple records.
5. Sequel currently has adapters for ADO, Amalgalite, DataObjects, DB2, DBI, Firebird, Informix, JDBC, MySQL, ODBC, OpenBase, Oracle, PostgreSQL and SQLite3.
   

Enhancements

• Add Dataset #set_defaults and #set_overrides, used for scoping the values used in insert/update statements
• Allow Models to use the RETURNING clause when inserting records on PostgreSQL
• Raise Sequel:DatabaseError instead of generic Sequel:Error for database errors, dont swallow tracebacks
• Use INSERT ... RETURNING ... with PostgreSQL 8.2 and higher
• Make insert_sql, delete_sql, and update_sql respect the :sql option
• Default to converting 2 digit years, use Sequel.convert_two_digit_years = false to get back the old behavior
• Make the PostgreSQL adapter with the pg driver use async_exec, so it doesnt block the entire interpreter
• Make the schema generators support composite primary and foreign keys and unique constraints
• Work with the 2008.08.17 version of the pg gem
• Disallow abuse of SQL function syntax for types (use :type=>:varchar, :size=>255 instead of :type=>:varchar[255])
• Quote index names when creating or dropping indexes
• Dont have column accessor methods override plugin instance methods
• Allow validation of multiple attributes at once, with built in support for uniqueness checking of multiple columns
• In PostgreSQL adapter, fix inserting a row with a primary key value inside a transaction
• Allow before_save and before_update to affect the columns saved by save_changes
• Make Dataset#single_value work when graphing, which fixes count and paginate on graphed datasets