class ActiveRecord::ConnectionAdapters::PostgreSQLAdapter

Parent:: ActiveRecord::ConnectionAdapters::AbstractAdapter
Included modules:: ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::Quoting, ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::ReferentialIntegrity, ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::SchemaStatements, ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::DatabaseStatements

The PostgreSQL adapter works with the native C (bitbucket.org/ged/ruby-pg) driver.

Options:

:host - Defaults to a Unix-domain socket in /tmp. On machines without Unix-domain sockets, the default is to connect to localhost.
:port - Defaults to 5432.
:username - Defaults to be the same as the operating system name of the user running the application.
:password - Password to be used if the server demands password authentication.
:database - Defaults to be the same as the user name.
:schema_search_path - An optional schema search path for the connection given as a string of comma-separated schema names. This is backward-compatible with the :schema_order option.
:encoding - An optional client encoding that is used in a SET client_encoding TO <encoding> call on the connection.
:min_messages - An optional client min messages that is used in a SET client_min_messages TO <min_messages> call on the connection.
:variables - An optional hash of additional parameters that will be used in SET SESSION key = val calls on the connection.
:insert_returning - An optional boolean to control the use or RETURNING for INSERT statements defaults to true.

Any further options are used as connection parameters to libpq. See www.postgresql.org/docs/9.1/static/libpq-connect.html for the list of parameters.

In addition, default connection parameters of libpq can be set per environment variables. See www.postgresql.org/docs/9.1/static/libpq-envars.html .

Constants

ADAPTER_NAME
FOREIGN_KEY_VIOLATION: See www.postgresql.org/docs/9.1/static/errcodes-appendix.html
NATIVE_DATABASE_TYPES
UNIQUE_VIOLATION

Public Class Methods

new(connection, logger, connection_parameters, config) Show source

Initializes and connects a PostgreSQL adapter.

Calls superclass method ActiveRecord::ConnectionAdapters::QueryCache.new

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 552
def initialize(connection, logger, connection_parameters, config)
  super(connection, logger)

  if self.class.type_cast_config_to_boolean(config.fetch(:prepared_statements) { true })
    @prepared_statements = true
    @visitor = Arel::Visitors::PostgreSQL.new self
  else
    @visitor = unprepared_visitor
  end

  @connection_parameters, @config = connection_parameters, config

  # @local_tz is initialized as nil to avoid warnings when connect tries to use it
  @local_tz = nil
  @table_alias_length = nil

  connect
  @statements = StatementPool.new @connection,
                                  self.class.type_cast_config_to_integer(config.fetch(:statement_limit) { 1000 })

  if postgresql_version < 80200
    raise "Your version of PostgreSQL (#{postgresql_version}) is too old, please upgrade!"
  end

  @type_map = OID::TypeMap.new
  initialize_type_map(type_map)
  @local_tz = execute('SHOW TIME ZONE', 'SCHEMA').first["TimeZone"]
  @use_insert_returning = @config.key?(:insert_returning) ? self.class.type_cast_config_to_boolean(@config[:insert_returning]) : true
end

Public Instance Methods

active?() Show source

Is this connection alive and ready for queries?

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 588
def active?
  @connection.query 'SELECT 1'
  true
rescue PGError
  false
end

active_threadsafe?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 595
def active_threadsafe?
  @connection.connect_poll != PG::PGRES_POLLING_FAILED
end

adapter_name() Show source

Returns 'PostgreSQL' as adapter name for identification purposes.

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 454
def adapter_name
  ADAPTER_NAME
end

clear_cache!() Show source

Clears the prepared statements cache.

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 583
def clear_cache!
  @statements.clear
end

disable_extension(name) Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 668
def disable_extension(name)
  exec_query("DROP EXTENSION IF EXISTS \"#{name}\" CASCADE").tap {
    reload_type_map
  }
end

disconnect!() Show source

Disconnects from the database if already connected. Otherwise, this method does nothing.

Calls superclass method ActiveRecord::ConnectionAdapters::AbstractAdapter#disconnect!

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 613
def disconnect!
  super
  @connection.close rescue nil
end

enable_extension(name) Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 662
def enable_extension(name)
  exec_query("CREATE EXTENSION IF NOT EXISTS \"#{name}\"").tap {
    reload_type_map
  }
end

extension_enabled?(name) Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 674
def extension_enabled?(name)
  if supports_extensions?
    res = exec_query "SELECT EXISTS(SELECT * FROM pg_available_extensions WHERE name = '#{name}' AND installed_version IS NOT NULL) as enabled",
      'SCHEMA'
    res.column_types['enabled'].type_cast res.rows.first.first
  end
end

extensions() Show source

Calls superclass method ActiveRecord::ConnectionAdapters::AbstractAdapter#extensions

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 682
def extensions
  if supports_extensions?
    res = exec_query "SELECT extname from pg_extension", "SCHEMA"
    res.rows.map { |r| res.column_types['extname'].type_cast r.first }
  else
    super
  end
end

index_algorithms() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 490
def index_algorithms
  { concurrently: 'CONCURRENTLY' }
end

migration_keys() Show source

Adds `:array` as a valid migration key

Calls superclass method ActiveRecord::ConnectionAdapters::ColumnDumper#migration_keys

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 468
def migration_keys
  super + [:array]
end

prepare_column_options(column, types) Show source

Adds `:array` option to the default set provided by the AbstractAdapter

Calls superclass method ActiveRecord::ConnectionAdapters::ColumnDumper#prepare_column_options

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 460
def prepare_column_options(column, types)
  spec = super
  spec[:array] = 'true' if column.respond_to?(:array) && column.array
  spec[:default] = "\"#{column.default_function}\"" if column.default_function
  spec
end

reconnect!() Show source

Close then reopen the connection.

Calls superclass method ActiveRecord::ConnectionAdapters::AbstractAdapter#reconnect!

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 600
def reconnect!
  super
  @connection.reset
  configure_connection
end

reset!() Show source

Calls superclass method ActiveRecord::ConnectionAdapters::AbstractAdapter#reset!

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 606
def reset!
  clear_cache!
  super
end

schema_creation() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 36
def schema_creation
  SchemaCreation.new self
end

session_auth=(user) Show source

Set the authorized user for this session

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 697
def session_auth=(user)
  clear_cache!
  exec_query "SET SESSION AUTHORIZATION #{user}"
end

set_standard_conforming_strings() Show source

Enable standard-conforming strings if available.

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 633
def set_standard_conforming_strings
  old, self.client_min_messages = client_min_messages, 'panic'
  execute('SET standard_conforming_strings = on', 'SCHEMA') rescue nil
ensure
  self.client_min_messages = old
end

supports_ddl_transactions?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 644
def supports_ddl_transactions?
  true
end

supports_explain?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 648
def supports_explain?
  true
end

supports_extensions?() Show source

Returns true if pg > 9.1

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 653
def supports_extensions?
  postgresql_version >= 90100
end

supports_index_sort_order?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 478
def supports_index_sort_order?
  true
end

supports_insert_with_returning?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 640
def supports_insert_with_returning?
  true
end

supports_migrations?() Show source

Returns true, since this connection adapter supports migrations.

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 623
def supports_migrations?
  true
end

supports_partial_index?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 482
def supports_partial_index?
  true
end

supports_ranges?() Show source

Range datatypes weren't introduced until PostgreSQL 9.2

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 658
def supports_ranges?
  postgresql_version >= 90200
end

supports_statement_cache?() Show source

Returns true, since this connection adapter supports prepared statement caching.

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 474
def supports_statement_cache?
  true
end

supports_transaction_isolation?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 486
def supports_transaction_isolation?
  true
end

table_alias_length() Show source

Returns the configured supported identifier length supported by PostgreSQL

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 692
def table_alias_length
  @table_alias_length ||= query('SHOW max_identifier_length', 'SCHEMA')[0][0].to_i
end

use_insert_returning?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 721
def use_insert_returning?
  @use_insert_returning
end

valid_type?(type) Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 725
def valid_type?(type)
  !native_database_types[type].nil?
end

Protected Instance Methods

postgresql_version() Show source

Returns the version of the connected PostgreSQL server.

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 736
def postgresql_version
  @connection.server_version
end

translate_exception(exception, message) Show source

Calls superclass method ActiveRecord::ConnectionAdapters::AbstractAdapter#translate_exception

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 744
def translate_exception(exception, message)
  return exception unless exception.respond_to?(:result)

  case exception.result.try(:error_field, PGresult::PG_DIAG_SQLSTATE)
  when UNIQUE_VIOLATION
    RecordNotUnique.new(message, exception)
  when FOREIGN_KEY_VIOLATION
    InvalidForeignKey.new(message, exception)
  else
    super
  end
end