Module: ActiveRecord::ConnectionAdapters::DatabaseStatements

Included in:
AbstractAdapter
Defined in:
activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#transaction_manager ⇒ Object (readonly)

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 439

def transaction_manager
  @transaction_manager
end

Instance Method Details

#_exec_insert(intent, pk = nil, sequence_name = nil, returning: nil) ⇒ Object

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 193

def _exec_insert(intent, pk = nil, sequence_name = nil, returning: nil) # :nodoc:
  sql, binds = sql_for_insert(intent.raw_sql, pk, intent.binds, returning)
  intent.raw_sql = sql
  intent.binds = binds

  intent.execute!
  intent.cast_result
end

#add_transaction_record(record, ensure_finalize = true) ⇒ Object

Register a record with the current transaction so that its after_commit and after_rollback callbacks can be called.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 472

def add_transaction_record(record, ensure_finalize = true)
  current_transaction.add_record(record, ensure_finalize)
end

#begin_db_transaction ⇒ Object

Begins the transaction (and turns off auto-committing).



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 477

def begin_db_transaction()    end

#begin_deferred_transaction(isolation_level = nil) ⇒ Object

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 479

def begin_deferred_transaction(isolation_level = nil) # :nodoc:
  if isolation_level
    begin_isolated_db_transaction(isolation_level)
  else
    begin_db_transaction
  end
end

#begin_isolated_db_transaction(isolation) ⇒ Object

Begins the transaction with the isolation level set. Raises an error by default; adapters that support setting the isolation level should implement this method.

Raises:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 502

def begin_isolated_db_transaction(isolation)
  raise ActiveRecord::TransactionIsolationError, "adapter does not support setting transaction isolation"
end

#cacheable_query(klass, arel) ⇒ Object

This is used in the StatementCache object. It returns an object that can be used to query the database repeatedly.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 55

def cacheable_query(klass, arel) # :nodoc:
  if prepared_statements
    collector = collector()
    collector.retryable = true
    sql, binds = visitor.compile(arel.ast, collector)
    query = klass.query(sql, retryable: collector.retryable)
  else
    collector = klass.partial_query_collector
    collector.retryable = true
    parts, binds = visitor.compile(arel.ast, collector)
    query = klass.partial_query(parts, retryable: collector.retryable)
  end
  [query, binds]
end

#commit_db_transaction ⇒ Object

Commits the transaction (and turns on auto-committing).



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 516

def commit_db_transaction()   end

#default_insert_value(column) ⇒ Object

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 600

def default_insert_value(column) # :nodoc:
  DEFAULT_INSERT_VALUE
end

#default_sequence_name(table, column) ⇒ Object 



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 538

def default_sequence_name(table, column)
  nil
end

#delete(arel, name = nil, binds = []) ⇒ Object

Executes the delete statement and returns the number of rows affected.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 263

def delete(arel, name = nil, binds = [])
  intent = QueryIntent.new(adapter: self, arel: arel, name: name, binds: binds)

  intent.execute!
  intent.affected_rows
end

#empty_all_tables ⇒ Object

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 568

def empty_all_tables # :nodoc:
  truncate_tables(*tables)
end

#empty_insert_statement_value(primary_key = nil) ⇒ Object 



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 572

def empty_insert_statement_value(primary_key = nil)
  "DEFAULT VALUES"
end

#exec_delete(sql, name = nil, binds = []) ⇒ Object

Executes delete sql statement in the context of this connection using binds as the bind substitutes. name is logged along with the executed sql statement.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 205

def exec_delete(sql, name = nil, binds = [])
  intent = internal_build_intent(sql, name, binds)
  intent.execute!
  intent.affected_rows
end

#exec_insert(sql, name = nil, binds = [], pk = nil, sequence_name = nil, returning: nil) ⇒ Object

Executes insert sql statement in the context of this connection using binds as the bind substitutes. name is logged along with the executed sql statement. Some adapters support the returning keyword argument which allows to control the result of the query: nil is the default value and maintains default behavior. If an array of column names is passed - the result will contain values of the specified columns from the inserted row.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 187

def exec_insert(sql, name = nil, binds = [], pk = nil, sequence_name = nil, returning: nil)
  intent = QueryIntent.new(adapter: self, raw_sql: sql, name: name, binds: binds)

  _exec_insert(intent, pk, sequence_name, returning: returning)
end

#exec_insert_all(sql, name) ⇒ Object

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 222

def exec_insert_all(sql, name) # :nodoc:
  intent = internal_build_intent(sql, name)
  intent.execute!
  intent.cast_result
end

#exec_query(sql, name = "SQL", binds = [], prepare: false) ⇒ Object

Executes sql statement in the context of this connection using binds as the bind substitutes. name is logged along with the executed sql statement.

Note: the query is assumed to have side effects and the query cache will be cleared. If the query is read-only, consider using #select_all instead.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 175

def exec_query(sql, name = "SQL", binds = [], prepare: false)
  intent = internal_build_intent(sql, name, binds, prepare: prepare)
  intent.execute!
  intent.cast_result
end

#exec_restart_db_transaction ⇒ Object

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 532

def exec_restart_db_transaction() end

#exec_rollback_db_transaction ⇒ Object

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 526

def exec_rollback_db_transaction() end

#exec_update(sql, name = nil, binds = []) ⇒ Object

Executes update sql statement in the context of this connection using binds as the bind substitutes. name is logged along with the executed sql statement.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 214

def exec_update(sql, name = nil, binds = [])
  intent = internal_build_intent(sql, name, binds)
  intent.execute!
  intent.affected_rows
end

#execute(sql, name = nil, allow_retry: false) ⇒ Object

Executes the SQL statement in the context of this connection and returns the raw result from the connection adapter.

Setting allow_retry to true causes the db to reconnect and retry executing the SQL statement in case of a connection-related exception. This option should only be enabled for known idempotent queries.

Note: the query is assumed to have side effects and the query cache will be cleared. If the query is read-only, consider using #select_all instead.

Note: depending on your database connector, the result returned by this method may be manually memory managed. Consider using #exec_query wrapper instead.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 162

def execute(sql, name = nil, allow_retry: false)
  intent = internal_build_intent(sql, name, allow_retry: allow_retry)
  intent.execute!
  intent.raw_result
end

#execute_batch(statements, name = nil, **kwargs) ⇒ Object

Executes SQL statements in the context of this connection without returning a result.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 620

def execute_batch(statements, name = nil, **kwargs) # :nodoc:
  statements.each do |statement|
    intent = QueryIntent.new(
      adapter: self,
      processed_sql: statement,
      name: name,
      binds: kwargs[:binds] || [],
      prepare: kwargs[:prepare] || false,
      allow_retry: kwargs[:allow_retry] || false,
      materialize_transactions: kwargs[:materialize_transactions] != false,
      batch: kwargs[:batch] || false
    )
    intent.execute!
    intent.finish
  end
end

#execute_intent(intent) ⇒ Object

Lowest-level abstract execution of a query, called only from the intent itself. Final wrapper around the subclass-specific perform_query. Populates the calling intent’s raw_result.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 607

def execute_intent(intent) # :nodoc:
  log(intent) do |notification_payload|
    intent.notification_payload = notification_payload
    with_raw_connection(allow_retry: intent.allow_retry, materialize_transactions: intent.materialize_transactions) do |conn|
      result = perform_query(conn, intent)
      intent.raw_result = result
      handle_warnings(result, intent.processed_sql)
    end
  end
end

#explain(arel, binds = [], options = []) ⇒ Object

:nodoc:

Raises:

  • (NotImplementedError) 


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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 228

def explain(arel, binds = [], options = []) # :nodoc:
  raise NotImplementedError
end

#high_precision_current_timestamp ⇒ Object

Returns an Arel SQL literal for the CURRENT_TIMESTAMP for usage with arbitrary precision date/time columns.

Adapters supporting datetime with precision should override this to provide as much precision as is available.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 596

def high_precision_current_timestamp
  HIGH_PRECISION_CURRENT_TIMESTAMP
end

#initialize ⇒ Object 



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 6

def initialize
  super
  reset_transaction
end

#insert(arel, name = nil, pk = nil, id_value = nil, sequence_name = nil, binds = [], returning: nil) ⇒ Object Also known as: create

Executes an INSERT query and returns the new record’s ID

id_value will be returned unless the value is nil, in which case the database will attempt to calculate the last inserted id and return that value.

If the next id was calculated in advance (as in Oracle), it should be passed in as id_value. Some adapters support the returning keyword argument which allows defining the return value of the method: nil is the default value and maintains default behavior. If an array of column names is passed - an array of is returned from the method representing values of the specified columns from the inserted row.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 243

def insert(arel, name = nil, pk = nil, id_value = nil, sequence_name = nil, binds = [], returning: nil)
  intent = QueryIntent.new(adapter: self, arel: arel, name: name, binds: binds)

  value = _exec_insert(intent, pk, sequence_name, returning: returning)

  return returning_column_values(value) unless returning.nil?

  id_value || last_inserted_id(value)
end

#insert_fixture(fixture, table_name) ⇒ Object

Inserts the given fixture into the table. Overridden in adapters that require something beyond a simple insert (e.g. Oracle). Most of adapters should implement insert_fixtures_set that leverages bulk SQL insert. We keep this method to provide fallback for databases like SQLite that do not support bulk inserts.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 552

def insert_fixture(fixture, table_name)
  execute(build_fixture_sql(Array.wrap(fixture), table_name), "Fixture Insert")
end

#insert_fixtures_set(fixture_set, tables_to_delete = []) ⇒ Object 



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 556

def insert_fixtures_set(fixture_set, tables_to_delete = [])
  fixture_inserts = build_fixture_statements(fixture_set)
  table_deletes = build_delete_from_statements(tables_to_delete)
  statements = table_deletes + fixture_inserts

  transaction(requires_new: true) do
    disable_referential_integrity do
      execute_batch(statements, "Fixtures Load")
    end
  end
end

#query_all(sql, name = "SCHEMA", allow_retry: true, materialize_transactions: false) ⇒ Object

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 131

def query_all(sql, name = "SCHEMA", allow_retry: true, materialize_transactions: false) # :nodoc:
  intent = internal_build_intent(sql, name, allow_retry:, materialize_transactions:)
  intent.execute!
  intent.cast_result
end

#query_command(sql, name = nil, allow_retry: false, materialize_transactions: true) ⇒ Object

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 137

def query_command(sql, name = nil, allow_retry: false, materialize_transactions: true) # :nodoc:
  intent = internal_build_intent(sql, name, allow_retry: allow_retry, materialize_transactions: materialize_transactions)
  intent.execute!
  intent.finish
end

#query_one ⇒ Object

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 123

def query_one(...) # :nodoc:
  query_all(...).first
end

#query_rows ⇒ Object

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 127

def query_rows(...) # :nodoc:
  query_all(...).rows
end

#query_value ⇒ Object

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 115

def query_value(...) # :nodoc:
  single_value_from_rows(query_rows(...))
end

#query_values ⇒ Object

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 119

def query_values(...) # :nodoc:
  query_rows(...).map(&:first)
end

#reset_isolation_level ⇒ Object

Hook point called after an isolated DB transaction is committed or rolled back. Most adapters don’t need to implement anything because the isolation level is set on a per transaction basis. But some databases like SQLite set it on a per connection level and need to explicitly reset it after commit or rollback.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 512

def reset_isolation_level
end

#reset_sequence!(table, column, sequence = nil) ⇒ Object

Set the sequence to the max value of the table’s column.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 543

def reset_sequence!(table, column, sequence = nil)
  # Do nothing by default. Implement for PostgreSQL, Oracle, ...
end

#reset_transaction(restore: false) ⇒ Object

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 450

def reset_transaction(restore: false) # :nodoc:
  # Store the existing transaction state to the side
  old_state = @transaction_manager if restore && @transaction_manager&.restorable?

  @transaction_manager = ConnectionAdapters::TransactionManager.new(self)

  if block_given?
    # Reconfigure the connection without any transaction state in the way
    result = yield

    # Now the connection's fully established, we can swap back
    if old_state
      @transaction_manager = old_state
      @transaction_manager.restore_transactions
    end

    result
  end
end

#restart_db_transaction ⇒ Object 



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 528

def restart_db_transaction
  exec_restart_db_transaction
end

#rollback_db_transaction ⇒ Object

Rolls back the transaction (and turns on auto-committing). Must be done if the transaction block raises an exception or returns false.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 520

def rollback_db_transaction
  exec_rollback_db_transaction
rescue ActiveRecord::ConnectionNotEstablished, ActiveRecord::ConnectionFailed
  # Connection's gone; that counts as a rollback
end

#rollback_to_savepoint(name = nil) ⇒ Object 



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 534

def rollback_to_savepoint(name = nil)
  exec_rollback_to_savepoint(name)
end

#select_all(arel, name = nil, binds = [], preparable: nil, async: false, allow_retry: false) ⇒ Object

Returns an ActiveRecord::Result instance.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 71

def select_all(arel, name = nil, binds = [], preparable: nil, async: false, allow_retry: false)
  arel = arel_from_relation(arel)
  intent = QueryIntent.new(
    adapter: self,
    arel: arel,
    name: name,
    binds: binds,
    prepare: preparable,
    allow_async: async,
    allow_retry: allow_retry
  )

  intent.execute!

  if async
    intent.future_result
  else
    intent.cast_result
  end
end

#select_one(arel, name = nil, binds = [], async: false) ⇒ Object

Returns a record hash with the column names as keys and column values as values.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 94

def select_one(arel, name = nil, binds = [], async: false)
  select_all(arel, name, binds, async: async).then(&:first)
end

#select_rows(arel, name = nil, binds = [], async: false) ⇒ Object

Returns an array of arrays containing the field values. Order is the same as that returned by columns.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 111

def select_rows(arel, name = nil, binds = [], async: false)
  select_all(arel, name, binds, async: async).then(&:rows)
end

#select_value(arel, name = nil, binds = [], async: false) ⇒ Object

Returns a single value from a record



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 99

def select_value(arel, name = nil, binds = [], async: false)
  select_rows(arel, name, binds, async: async).then { |rows| single_value_from_rows(rows) }
end

#select_values(arel, name = nil, binds = []) ⇒ Object

Returns an array of the values of the first column in a select:

select_values("SELECT id FROM companies LIMIT 3") => [1,2,3]



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 105

def select_values(arel, name = nil, binds = [])
  select_rows(arel, name, binds).map(&:first)
end

#to_sql(arel_or_sql_string, binds = []) ⇒ Object

Converts an arel AST to SQL



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 12

def to_sql(arel_or_sql_string, binds = [])
  sql, _ = to_sql_and_binds(arel_or_sql_string, binds)
  sql
end

#to_sql_and_binds(arel_or_sql_string, binds = [], preparable = nil, allow_retry = false) ⇒ Object

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 17

def to_sql_and_binds(arel_or_sql_string, binds = [], preparable = nil, allow_retry = false) # :nodoc:
  # Arel::TreeManager -> Arel::Node
  if arel_or_sql_string.respond_to?(:ast)
    arel_or_sql_string = arel_or_sql_string.ast
  end

  if Arel.arel_node?(arel_or_sql_string) && !(String === arel_or_sql_string)
    unless binds.empty?
      raise "Passing bind parameters with an arel AST is forbidden. " \
        "The values must be stored on the AST directly"
    end

    collector = collector()
    collector.retryable = true

    if prepared_statements
      collector.preparable = true
      sql, binds = visitor.compile(arel_or_sql_string, collector)

      if binds.length > bind_params_length
        unprepared_statement do
          return to_sql_and_binds(arel_or_sql_string)
        end
      end
      preparable = collector.preparable
    else
      sql = visitor.compile(arel_or_sql_string, collector)
    end
    allow_retry = collector.retryable
    [sql.freeze, binds, preparable, allow_retry]
  else
    arel_or_sql_string = arel_or_sql_string.dup.freeze unless arel_or_sql_string.frozen?
    [arel_or_sql_string, binds, preparable, allow_retry]
  end
end

#transaction(requires_new: nil, isolation: nil, joinable: true, &block) ⇒ Object

Runs the given block in a database transaction, and returns the result of the block.

Transaction callbacks

#transaction yields an ActiveRecord::Transaction object on which it is possible to register callback:

ActiveRecord::Base.transaction do |transaction|
  transaction.before_commit { puts "before commit!" }
  transaction.after_commit { puts "after commit!" }
  transaction.after_rollback { puts "after rollback!" }
end

Nested transactions support

#transaction calls can be nested. By default, this makes all database statements in the nested transaction block become part of the parent transaction. For example, the following behavior may be surprising:

ActiveRecord::Base.transaction do
  Post.create(title: 'first')
  ActiveRecord::Base.transaction do
    Post.create(title: 'second')
    raise ActiveRecord::Rollback
  end
end

This creates both “first” and “second” posts. Reason is the ActiveRecord::Rollback exception in the nested block does not issue a ROLLBACK. Since these exceptions are captured in transaction blocks, the parent block does not see it and the real transaction is committed.

Most databases don’t support true nested transactions. At the time of writing, the only database that supports true nested transactions that we’re aware of, is MS-SQL.

In order to get around this problem, #transaction will emulate the effect of nested transactions, by using savepoints: dev.mysql.com/doc/refman/en/savepoint.html.

It is safe to call this method if a database transaction is already open, i.e. if #transaction is called within another #transaction block. In case of a nested call, #transaction will behave as follows:

  • The block will be run without doing anything. All database statements that happen within the block are effectively appended to the already open database transaction.

  • However, if :requires_new is set, the block will be wrapped in a database savepoint acting as a sub-transaction.

In order to get a ROLLBACK for the nested transaction you may ask for a real sub-transaction by passing requires_new: true. If anything goes wrong, the database rolls back to the beginning of the sub-transaction without rolling back the parent transaction. If we add it to the previous example:

ActiveRecord::Base.transaction do
  Post.create(title: 'first')
  ActiveRecord::Base.transaction(requires_new: true) do
    Post.create(title: 'second')
    raise ActiveRecord::Rollback
  end
end

only post with title “first” is created.

See ActiveRecord::Transactions to learn more.

Caveats

MySQL doesn’t support DDL transactions. If you perform a DDL operation, then any created savepoints will be automatically released. For example, if you’ve created a savepoint, then you execute a CREATE TABLE statement, then the savepoint that was created will be automatically released.

This means that, on MySQL, you shouldn’t execute DDL operations inside a #transaction call that you know might create a savepoint. Otherwise, #transaction will raise exceptions when it tries to release the already-automatically-released savepoints:

Model.lease_connection.transaction do  # BEGIN
  Model.lease_connection.transaction(requires_new: true) do  # CREATE SAVEPOINT active_record_1
    Model.lease_connection.create_table(...)
    # active_record_1 now automatically released
  end  # RELEASE SAVEPOINT active_record_1  <--- BOOM! database error!
end

Transaction isolation

If your database supports setting the isolation level for a transaction, you can set it like so:

Post.transaction(isolation: :serializable) do
  # ...
end

Valid isolation levels are:

  • :read_uncommitted

  • :read_committed

  • :repeatable_read

  • :serializable

You should consult the documentation for your database to understand the semantics of these different levels:

An ActiveRecord::TransactionIsolationError will be raised if:

  • The adapter does not support setting the isolation level

  • You are joining an existing open transaction

  • You are creating a nested (savepoint) transaction

The mysql2, trilogy, and postgresql adapters support setting the transaction isolation level.

:args: (requires_new: nil, isolation: nil, &block)



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 405

def transaction(requires_new: nil, isolation: nil, joinable: true, &block)
  # If we're running inside the single, non-joinable transaction that
  # ActiveRecord::TestFixtures starts around each example (depth == 1),
  # an `isolation:` hint must be validated then ignored so that the
  # adapter isn't asked to change the isolation level mid-transaction.
  isolation_override = false
  if isolation && open_transactions == 1 && !current_transaction.joinable?
    iso = isolation.to_sym

    unless transaction_isolation_levels.include?(iso)
      raise ActiveRecord::TransactionIsolationError,
            "invalid transaction isolation level: #{iso.inspect}"
    end

    isolation_override = true
    old_isolation = current_transaction.isolation
    current_transaction.isolation = iso
    isolation = nil
  end

  if !requires_new && current_transaction.joinable?
    if isolation && current_transaction.isolation != isolation
      raise ActiveRecord::TransactionIsolationError, "cannot set isolation when joining a transaction"
    end
    yield current_transaction.user_transaction
  else
    within_new_transaction(isolation: isolation, joinable: joinable, &block)
  end
rescue ActiveRecord::Rollback
  # rollbacks are silently swallowed
ensure
  current_transaction.isolation = old_isolation if isolation_override
end

#transaction_isolation_levels ⇒ Object 



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 495

def transaction_isolation_levels
  TRANSACTION_ISOLATION_LEVELS
end

#transaction_open? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 446

def transaction_open?
  current_transaction.open?
end

#truncate(table_name, name = nil) ⇒ Object

Executes the truncate statement.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 271

def truncate(table_name, name = nil)
  execute(build_truncate_statement(table_name), name)
end

#truncate_tables(*table_names) ⇒ Object

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 275

def truncate_tables(*table_names) # :nodoc:
  table_names -= [pool.schema_migration.table_name, pool.internal_metadata.table_name]

  return if table_names.empty?

  disable_referential_integrity do
    statements = build_truncate_statements(table_names)
    execute_batch(statements, "Truncate Tables")
  end
end

#update(arel, name = nil, binds = []) ⇒ Object

Executes the update statement and returns the number of rows affected.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 255

def update(arel, name = nil, binds = [])
  intent = QueryIntent.new(adapter: self, arel: arel, name: name, binds: binds)

  intent.execute!
  intent.affected_rows
end

#with_yaml_fallback(value) ⇒ Object

Fixture value is quoted by Arel, however scalar values are not quotable. In this case we want to convert the column value to YAML.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 579

def with_yaml_fallback(value) # :nodoc:
  if value.is_a?(Hash) || value.is_a?(Array)
    YAML.dump(value)
  else
    value
  end
end

#write_query?(sql) ⇒ Boolean

Determines whether the SQL statement is a write query.

Returns:

  • (Boolean)

Raises:

  • (NotImplementedError) 


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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 144

def write_query?(sql)
  raise NotImplementedError
end