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Refactor dead lock victim retry code.
 * Put custom #transaction method into core ext module. * Our #transaction method does not bind &block but yields in anonymous block. * Organize connection tests with context block at bottom.
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‎CHANGELOG‎

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@@ -1,6 +1,8 @@
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* master *
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* New deadlock victim retry using the #retry_deadlock_victim config. [Joe Rafaniello]
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* Renamed #with_auto_reconnect to #with_sqlserver_error_handling now that it handles both dropped
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connections and deadlock victim errors. Fixes #150 [Joe Rafaniello]
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‎README.md‎

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@@ -6,6 +6,7 @@ The SQL Server adapter for ActiveRecord. If you need the adapter for SQL Server
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## What's New
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* Deadlock victim retry logic using the #retry_deadlock_victim config.
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* Proper interface to configure the connection and TinyTDS app name reported to SQL Server.
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* Rails 3.1 prepared statement support leverages cached query plans.
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If you use DBLIB/TinyTDS, you must use FreeTDS 0.91 !!!!!
@@ -111,6 +112,15 @@ ActiveRecord::ConnectionAdapters::SQLServerAdapter.native_string_database_type =
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It is important to remember that unicode types in SQL Server have approximately half the storage capacity as their counter parts. So where a normal string would max out at (8000) a unicode string will top off at (4000).
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#### Deadlock Victim Retry
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In a config initializer, you can configure the adapter to retry deadlock victims' SQL. Note, this relies on us copying ActiveRecord's `#transaction` method and can be brittle when upgrading. If you think that our version of `#transaction` is out of sync with the version of rails in our gemspec, please open a ticket and let us know. Our custom transaction method can be found in `activerecord/connection_adapters/sqlserver/core_ext/database_statements.rb`.
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```ruby
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ActiveRecord::ConnectionAdapters::SQLServerAdapter.retry_deadlock_victim = true
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```
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#### Force Schema To Lowercase
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Although it is not necessary, the Ruby convention is to use lowercase method names. If your database schema is in upper or mixed case, we can force all table and column names during the schema reflection process to be lowercase. Add this to your config/initializers file for the adapter.

‎activerecord-sqlserver-adapter.gemspec‎

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@@ -17,6 +17,6 @@ Gem::Specification.new do |s|
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s.require_path = 'lib'
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s.rubyforge_project = 'activerecord-sqlserver-adapter'
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s.add_dependency('activerecord', '~> 3.1.0')
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s.add_dependency('activerecord', '~> 3.1.3')
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end
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‎lib/active_record/connection_adapters/sqlserver/core_ext/database_statements.rb‎

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module ActiveRecord
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module ConnectionAdapters
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module Sqlserver
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module CoreExt
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module DatabaseStatements
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# This is a copy of the current (3.1.3) ActiveRecord's transaction method. We should propose
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# a patch to the default transaction method to make it more callback for adapters that want to
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# do deadlock retry logic. Because this is a copy, we really need to keep an eye out on this when
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# upgradding the adapter.
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def transaction_with_retry_deadlock_victim(options = {})
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options.assert_valid_keys :requires_new, :joinable
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last_transaction_joinable = defined?(@transaction_joinable) ? @transaction_joinable : nil
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if options.has_key?(:joinable)
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@transaction_joinable = options[:joinable]
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else
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@transaction_joinable = true
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end
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requires_new = options[:requires_new] || !last_transaction_joinable
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transaction_open = false
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@_current_transaction_records ||= []
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begin
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if block_given?
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if requires_new || open_transactions == 0
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if open_transactions == 0
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begin_db_transaction
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elsif requires_new
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create_savepoint
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end
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increment_open_transactions
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transaction_open = true
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@_current_transaction_records.push([])
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end
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yield
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end
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rescue Exception => database_transaction_rollback
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if transaction_open && !outside_transaction?
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transaction_open = false
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decrement_open_transactions
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# handle deadlock victim retries at the outermost transaction
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if open_transactions == 0
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if database_transaction_rollback.is_a?(::ActiveRecord::DeadlockVictim)
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# SQL Server has already rolled back, so rollback activerecord's history
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rollback_transaction_records(true)
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retry
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else
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rollback_db_transaction
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rollback_transaction_records(true)
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end
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else
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rollback_to_savepoint
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rollback_transaction_records(false)
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end
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end
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raise unless database_transaction_rollback.is_a?(::ActiveRecord::Rollback)
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end
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ensure
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@transaction_joinable = last_transaction_joinable
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if outside_transaction?
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@open_transactions = 0
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elsif transaction_open
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decrement_open_transactions
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begin
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if open_transactions == 0
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commit_db_transaction
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commit_transaction_records
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else
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release_savepoint
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save_point_records = @_current_transaction_records.pop
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unless save_point_records.blank?
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@_current_transaction_records.push([]) if @_current_transaction_records.empty?
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@_current_transaction_records.last.concat(save_point_records)
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end
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end
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rescue Exception => database_transaction_rollback
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if open_transactions == 0
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rollback_db_transaction
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rollback_transaction_records(true)
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else
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rollback_to_savepoint
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rollback_transaction_records(false)
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end
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raise
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end
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end
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end
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end
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end
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end
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end
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end
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‎lib/active_record/connection_adapters/sqlserver/database_statements.rb‎

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@@ -3,6 +3,8 @@ module ConnectionAdapters
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module Sqlserver
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module DatabaseStatements
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include CoreExt::DatabaseStatements
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def select_rows(sql, name = nil)
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raw_select sql, name, [], :fetch => :rows
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end
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true
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end
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def transaction(options = {}, &block)
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retry_deadlock_victim? ? transaction_with_retry_deadlock_victim(options, &block) : super(options, &block)
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end
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def transaction_with_retry_deadlock_victim(options = {})
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options.assert_valid_keys :requires_new, :joinable
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last_transaction_joinable = defined?(@transaction_joinable) ? @transaction_joinable : nil
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if options.has_key?(:joinable)
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@transaction_joinable = options[:joinable]
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def transaction(options = {})
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if retry_deadlock_victim?
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block_given? ? transaction_with_retry_deadlock_victim(options) { yield } : transaction_with_retry_deadlock_victim(options)
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else
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@transaction_joinable = true
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end
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requires_new = options[:requires_new] || !last_transaction_joinable
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transaction_open = false
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@_current_transaction_records ||= []
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begin
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if block_given?
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if requires_new || open_transactions == 0
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if open_transactions == 0
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begin_db_transaction
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elsif requires_new
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create_savepoint
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end
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increment_open_transactions
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transaction_open = true
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@_current_transaction_records.push([])
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end
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yield
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end
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rescue Exception => database_transaction_rollback
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if transaction_open && !outside_transaction?
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transaction_open = false
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decrement_open_transactions
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# handle deadlock victim retries at the outermost transaction
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if open_transactions == 0
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if database_transaction_rollback.is_a?(DeadlockVictim)
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# SQL Server has already rolled back, so rollback activerecord's history
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rollback_transaction_records(true)
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retry
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else
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rollback_db_transaction
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rollback_transaction_records(true)
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end
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else
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rollback_to_savepoint
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rollback_transaction_records(false)
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end
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end
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raise unless database_transaction_rollback.is_a?(ActiveRecord::Rollback)
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end
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ensure
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@transaction_joinable = last_transaction_joinable
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if outside_transaction?
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@open_transactions = 0
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elsif transaction_open
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decrement_open_transactions
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begin
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if open_transactions == 0
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commit_db_transaction
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commit_transaction_records
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else
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release_savepoint
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save_point_records = @_current_transaction_records.pop
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unless save_point_records.blank?
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@_current_transaction_records.push([]) if @_current_transaction_records.empty?
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@_current_transaction_records.last.concat(save_point_records)
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end
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end
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rescue Exception => database_transaction_rollback
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if open_transactions == 0
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rollback_db_transaction
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rollback_transaction_records(true)
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else
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rollback_to_savepoint
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rollback_transaction_records(false)
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end
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raise
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end
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block_given? ? super(options) { yield } : super(options)
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end
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end
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‎lib/active_record/connection_adapters/sqlserver_adapter.rb‎

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require 'active_record'
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require 'active_record/connection_adapters/abstract_adapter'
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require 'active_record/connection_adapters/sqlserver/core_ext/active_record'
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require 'active_record/connection_adapters/sqlserver/core_ext/database_statements'
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require 'active_record/connection_adapters/sqlserver/database_limits'
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require 'active_record/connection_adapters/sqlserver/database_statements'
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require 'active_record/connection_adapters/sqlserver/errors'
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rescue Exception => e
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case translate_exception(e,e.message)
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when LostConnection; retry if auto_reconnected?
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when DeadlockVictim; retry if retry_deadlock_victim? && self.open_transactions == 0
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when DeadlockVictim; retry if retry_deadlock_victim? && open_transactions == 0
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end
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raise
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end

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