# 3.35.0.txt

Path: | doc/release_notes/3.35.0.txt
Last Update: | Sun May 19 07:59:58 +0000 2013

# New Features

- A dirty plugin has been added, which saves the initial value of the column when the column is changed, similar to ActiveModel::Dirty:

        artist.name                   # => 'Foo'
        artist.name = 'Bar'
        artist.initial_value(:name)   # 'Foo'
        artist.column_change(:name)   # ['Foo', 'Bar']
        artist.column_changes         # {:name => ['Foo', 'Bar']}
        artist.column_changed?(:name) # true
        artist.reset_column(:name)
        artist.name                   # => 'Foo'
        artist.column_changed?(:name) # false
        artist.update(:name=>'Bar')
        artist.column_changes         # => {}
        artist.previous_changes       # => {:name=>['Foo', 'Bar']}

- Database#create_table now respects an :as option to create a database based on the results of a query. The :as option value should either be an SQL string or a dataset.

        DB.create_table(:new_foos, :as=>DB[:foos].where(:new=>true))

- The json_serializer and xml_serializer plugins can now serialize arbitrary arrays of model objects by passing an :array option to the to_json class method. This works around an issue in ruby‘s JSON library where Array#to_json does not pass arguments given to it to the members of the array.

        Artist.to_json(:array=>[Artist[1]], :include=>:albums)

- You can now use the % (modulus) operator in the same way you can use the bitwise operators in Sequel:

        :column.sql_number % 1 # (column % 1)

- On PostgreSQL, you can now provide :only, :cascade, and :restart options to Dataset#truncate to use ONLY, CASCADE, and RESTART IDENTITY. Additionally, you can now truncate multiple tables at the same time:

        DB.from(:table1, :table2).truncate(:cascade=>true)

- The :index option when creating columns in the schema generator can now take a hash of index options:

        DB.create_table(:foo){Integer :bar, :index=>{:unique=>true}}

- A Database#cache_schema accessor has been added, it can be set to false to have the Database never cache schema results. This can be useful in Rails development mode, so that you don‘t need to restart a running server to have models pick up the new schema.
- Database#log_exception has been added for easier instrumentation. It is called with the exception and SQL query string for all queries that raise an exception.
- The Sequel.migration DSL now has a transaction method that forces transaction use for the given migration.

# Other Improvements

- Many theoretical thread-safety issues have been fixed for ruby implementations that don‘t use a global interpreter lock. Previously, Sequel relied on MRI‘s global interpreter lock for part of its thread safety, now it does manually locking in more places to avoid thread-safety issues on JRuby (and other ruby implementations without a global interpreter lock).

  No Sequel user ever reported a production error related to the previous thread-safety issues, and most of the issues fixed were so difficult to hit that even tests specifically designed to raise errors were unable to do so.

- Sequel.single_threaded = true now disables the mutex synchronization that enforces thread safety for additional performance in single threaded mode.
- Sequel‘s migrators now only attempt to use transactions by default if the underlying database supports transactional DDL. SQLite does support transactional DDL, but Sequel will not use transactions for SQLite migrations as it causes issues when emulating alter_table operations for tables with foreign keys.
- Errors that occur when rolling back database transactions are now handled correctly. Previously, the underlying exception was raised, it wasn‘t correctly wrapped in a Sequel::DatabaseError, and if it was due to a database disconnection, the connection wasn‘t removed from the pool.
- Sequel no longer sets ruby instance variables on java objects, fixing warnings on JRuby 1.7 and attempting to be forward compatible with JRuby 2.0.
- Sequel now uses date and timestamp formats that are multilanguage and not DATEFORMAT dependent on Microsoft SQL Server.
- Sequel now correctly escapes blackslash-carriage return-line feed on Microsoft SQL Server.
- Parsing the column default values in the oracle adapter no longer requires database superuser privileges.
- Sequel now correctly handles parsing schema for tables in other databases on MySQL. Previously, it would always look in the current database.
- Sequel no longer doubles backslashes in strings by default. It now only does so on MySQL, since that is the only database that appears to use backslashes for escaping. This fixes issues with backslashes being doubled on some of the less commonly used adapters.
- The pg_auto_parameterize extension now works correctly when using cursors.
- Dataset#truncate now raises an Error if you attempt to do so on a dataset that uses HAVING. Previously, it only checked for WHERE.
- The schema dumper now recognized the identity type.

# Backwards Compatibility

- Association reflections now store cached information in a separate subhash due to the thread-safety changes. Any code accessing an association reflection should always call the related method to get the cached data instead of checking for a specific location in the hash.
- Association reflection internals for many_through_many associations changed significantly, any code that accesses the edge information in the reflection will need to be changed to use the new methods instead of accessing the old values directly.
- The features deprecated in 3.34.0 have now been removed:
  - Ruby <1.8.7 support
  - PostgreSQL <8.2 support
  - Dataset#disable_insert_returning on PostgreSQL
  - Array#all_two_pairs? and sql_expr_if_all_two_pairs

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