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Merge pull request #9507 from senny/9483_migrations_without_transactions

Transactions can be turned off per Migration
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commit 4ce98432512d11ac2f0330e2313c2c031552ffff 2 parents ac13b4d + b337390
@rafaelfranca rafaelfranca authored
View
15 activerecord/CHANGELOG.md
@@ -1,5 +1,20 @@
## Rails 4.0.0 (unreleased) ##
+* Make it possible to execute migrations without a transaction even
+ if the database adapter supports DDL transactions.
+ Fixes #9483.
+
+ Example:
+
+ class ChangeEnum < ActiveRecord::Migration
+ self.disable_ddl_transaction!
+ def up
+ execute "ALTER TYPE model_size ADD VALUE 'new_value'"
+ end
+ end
+
+ *Yves Senn*
+
* Assigning "0.0" to a nullable numeric column does not make it dirty.
Fix #9034.
View
44 activerecord/lib/active_record/migration.rb
@@ -330,6 +330,23 @@ def initialize
#
# For a list of commands that are reversible, please see
# <tt>ActiveRecord::Migration::CommandRecorder</tt>.
+ #
+ # == Transactional Migrations
+ #
+ # If the database adapter supports DDL transactions, all migrations will
+ # automatically be wrapped in a transaction. There are queries that you
+ # can't execute inside a transaction though, and for these situations
+ # you can turn the automatic transactions off.
+ #
+ # class ChangeEnum < ActiveRecord::Migration
+ # self.disable_ddl_transaction!
+ # def up
+ # execute "ALTER TYPE model_size ADD VALUE 'new_value'"
+ # end
+ # end
+ #
+ # Remember that you can still open your own transactions, even if you
+ # are in a Migration with <tt>self.disable_ddl_transaction!</tt>.
class Migration
autoload :CommandRecorder, 'active_record/migration/command_recorder'
@@ -351,6 +368,7 @@ def call(env)
class << self
attr_accessor :delegate # :nodoc:
+ attr_accessor :disable_ddl_transaction # :nodoc:
end
def self.check_pending!
@@ -365,8 +383,16 @@ def self.migrate(direction)
new.migrate direction
end
- cattr_accessor :verbose
+ # Disable DDL transactions for this migration.
+ def self.disable_ddl_transaction!
+ @disable_ddl_transaction = true
+ end
+
+ def disable_ddl_transaction # :nodoc:
+ self.class.disable_ddl_transaction
+ end
+ cattr_accessor :verbose
attr_accessor :name, :version
def initialize(name = self.class.name, version = nil)
@@ -375,8 +401,8 @@ def initialize(name = self.class.name, version = nil)
@connection = nil
end
+ self.verbose = true
# instantiate the delegate object after initialize is defined
- self.verbose = true
self.delegate = new
# Reverses the migration commands for the given block and
@@ -663,7 +689,7 @@ def basename
File.basename(filename)
end
- delegate :migrate, :announce, :write, :to => :migration
+ delegate :migrate, :announce, :write, :disable_ddl_transaction, to: :migration
private
@@ -856,12 +882,12 @@ def migrate
Base.logger.info "Migrating to #{migration.name} (#{migration.version})" if Base.logger
begin
- ddl_transaction do
+ ddl_transaction(migration) do
migration.migrate(@direction)
record_version_state_after_migrating(migration.version)
end
rescue => e
- canceled_msg = Base.connection.supports_ddl_transactions? ? "this and " : ""
+ canceled_msg = use_transaction?(migration) ? "this and " : ""
raise StandardError, "An error has occurred, #{canceled_msg}all later migrations canceled:\n\n#{e}", e.backtrace
end
end
@@ -935,12 +961,16 @@ def down?
end
# Wrap the migration in a transaction only if supported by the adapter.
- def ddl_transaction
- if Base.connection.supports_ddl_transactions?
+ def ddl_transaction(migration)
+ if use_transaction?(migration)
Base.transaction { yield }
else
yield
end
end
+
+ def use_transaction?(migration)
+ !migration.disable_ddl_transaction && Base.connection.supports_ddl_transactions?
+ end
end
end
View
2  activerecord/test/cases/migration/logger_test.rb
@@ -7,6 +7,7 @@ class LoggerTest < ActiveRecord::TestCase
self.use_transactional_fixtures = false
Migration = Struct.new(:name, :version) do
+ def disable_ddl_transaction; false end
def migrate direction
# do nothing
end
@@ -34,4 +35,3 @@ def test_migration_should_be_run_without_logger
end
end
end
-
View
42 activerecord/test/cases/migration_test.rb
@@ -239,9 +239,13 @@ def test_migrator_one_up_with_exception_and_rollback
assert_not Person.column_methods_hash.include?(:last_name)
- migration = Struct.new(:name, :version) {
- def migrate(x); raise 'Something broke'; end
- }.new('zomg', 100)
+ migration = Class.new(ActiveRecord::Migration) {
+ def version; 100 end
+ def migrate(x)
+ add_column "people", "last_name", :string
+ raise 'Something broke'
+ end
+ }.new
migrator = ActiveRecord::Migrator.new(:up, [migration], 100)
@@ -250,7 +254,39 @@ def migrate(x); raise 'Something broke'; end
assert_equal "An error has occurred, this and all later migrations canceled:\n\nSomething broke", e.message
Person.reset_column_information
+ assert_not Person.column_methods_hash.include?(:last_name),
+ "On error, the Migrator should revert schema changes but it did not."
+ end
+
+ def test_migration_without_transaction
+ unless ActiveRecord::Base.connection.supports_ddl_transactions?
+ skip "not supported on #{ActiveRecord::Base.connection.class}"
+ end
+
assert_not Person.column_methods_hash.include?(:last_name)
+
+ migration = Class.new(ActiveRecord::Migration) {
+ self.disable_ddl_transaction!
+
+ def version; 101 end
+ def migrate(x)
+ add_column "people", "last_name", :string
+ raise 'Something broke'
+ end
+ }.new
+
+ migrator = ActiveRecord::Migrator.new(:up, [migration], 101)
+ e = assert_raise(StandardError) { migrator.migrate }
+ assert_equal "An error has occurred, all later migrations canceled:\n\nSomething broke", e.message
+
+ Person.reset_column_information
+ assert Person.column_methods_hash.include?(:last_name),
+ "without ddl transactions, the Migrator should not rollback on error but it did."
+ ensure
+ Person.reset_column_information
+ if Person.column_methods_hash.include?(:last_name)
+ Person.connection.remove_column('people', 'last_name')
+ end
end
def test_schema_migrations_table_name
View
6 guides/source/migrations.md
@@ -61,6 +61,10 @@ migrations are wrapped in a transaction. If the database does not support this
then when a migration fails the parts of it that succeeded will not be rolled
back. You will have to rollback the changes that were made by hand.
+NOTE: There are certain queries that can't run inside a transaction. If your
+adapter supports DDL transactions you can use `disable_ddl_transaction!` to
+disable them for a single migration.
+
If you wish for a migration to do something that Active Record doesn't know how
to reverse, you can use `reversible`:
@@ -180,7 +184,7 @@ end
```
If the migration name is of the form "CreateXXX" and is
-followed by a list of column names and types then a migration creating the table
+followed by a list of column names and types then a migration creating the table
XXX with the columns listed will be generated. For example:
```bash
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