class ActiveRecord::ConnectionAdapters::PostgreSQLAdapter

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

Options:

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) click to toggle source

Initializes and connects a PostgreSQL adapter.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 226
def initialize(connection, logger, connection_parameters, config)
  super(connection, logger)

  @visitor = Arel::Visitors::PostgreSQL.new self
  if self.class.type_cast_config_to_boolean(config.fetch(:prepared_statements) { true })
    @prepared_statements = true
  else
    @prepared_statements = false
  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 = Type::HashLookupTypeMap.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?() click to toggle source

Is this connection alive and ready for queries?

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 266
def active?
  @connection.query 'SELECT 1'
  true
rescue PGError
  false
end
clear_cache!() click to toggle source

Clears the prepared statements cache.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 257
def clear_cache!
  @statements.clear
end
disable_extension(name) click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 343
def disable_extension(name)
  exec_query("DROP EXTENSION IF EXISTS \"#{name}\" CASCADE").tap {
    reload_type_map
  }
end
disconnect!() click to toggle source

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

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 292
def disconnect!
  super
  @connection.close rescue nil
end
enable_extension(name) click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 337
def enable_extension(name)
  exec_query("CREATE EXTENSION IF NOT EXISTS \"#{name}\"").tap {
    reload_type_map
  }
end
extension_enabled?(name) click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 349
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.cast_values.first
  end
end
extensions() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 357
def extensions
  if supports_extensions?
    exec_query("SELECT extname from pg_extension", "SCHEMA").cast_values
  else
    super
  end
end
index_algorithms() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 168
def index_algorithms
  { concurrently: 'CONCURRENTLY' }
end
migration_keys() click to toggle source

Adds :array as a valid migration key

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 138
def migration_keys
  super + [:array]
end
reconnect!() click to toggle source

Close then reopen the connection.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 274
def reconnect!
  super
  @connection.reset
  configure_connection
end
reset!() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 280
def reset!
  clear_cache!
  reset_transaction
  unless @connection.transaction_status == ::PG::PQTRANS_IDLE
    @connection.query 'ROLLBACK'
  end
  @connection.query 'DISCARD ALL'
  configure_connection
end
session_auth=(user) click to toggle source

Set the authorized user for this session

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 371
def session_auth=(user)
  clear_cache!
  exec_query "SET SESSION AUTHORIZATION #{user}"
end
set_standard_conforming_strings() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 311
def set_standard_conforming_strings
  execute('SET standard_conforming_strings = on', 'SCHEMA')
end
supports_ddl_transactions?() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 315
def supports_ddl_transactions?
  true
end
supports_explain?() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 319
def supports_explain?
  true
end
supports_extensions?() click to toggle source

Returns true if pg > 9.1

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 324
def supports_extensions?
  postgresql_version >= 90100
end
supports_foreign_keys?() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 160
def supports_foreign_keys?
  true
end
supports_index_sort_order?() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 148
def supports_index_sort_order?
  true
end
supports_materialized_views?() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 333
def supports_materialized_views?
  postgresql_version >= 90300
end
supports_migrations?() click to toggle source

Returns true, since this connection adapter supports migrations.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 302
def supports_migrations?
  true
end
supports_partial_index?() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 152
def supports_partial_index?
  true
end
supports_ranges?() click to toggle source

Range datatypes weren't introduced until PostgreSQL 9.2

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 329
def supports_ranges?
  postgresql_version >= 90200
end
supports_statement_cache?() click to toggle source

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

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 144
def supports_statement_cache?
  true
end
supports_transaction_isolation?() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 156
def supports_transaction_isolation?
  true
end
supports_views?() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 164
def supports_views?
  true
end
table_alias_length() click to toggle source

Returns the configured supported identifier length supported by PostgreSQL

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 366
def table_alias_length
  @table_alias_length ||= query('SHOW max_identifier_length', 'SCHEMA')[0][0].to_i
end
truncate(table_name, name = nil) click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 261
def truncate(table_name, name = nil)
  exec_query "TRUNCATE TABLE #{quote_table_name(table_name)}", name, []
end
use_insert_returning?() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 376
def use_insert_returning?
  @use_insert_returning
end
valid_type?(type) click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 380
def valid_type?(type)
  !native_database_types[type].nil?
end

Protected Instance Methods

postgresql_version() click to toggle source

Returns the version of the connected PostgreSQL server.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 406
def postgresql_version
  @connection.server_version
end
translate_exception(exception, message) click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 414
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

Private Instance Methods

configure_connection() click to toggle source

Configures the encoding, verbosity, schema search path, and time zone of the connection. This is called by connect and should not be called manually.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 669
def configure_connection
  if @config[:encoding]
    @connection.set_client_encoding(@config[:encoding])
  end
  self.client_min_messages = @config[:min_messages] || 'warning'
  self.schema_search_path = @config[:schema_search_path] || @config[:schema_order]

  # Use standard-conforming strings so we don't have to do the E'...' dance.
  set_standard_conforming_strings

  # If using Active Record's time zone support configure the connection to return
  # TIMESTAMP WITH ZONE types in UTC.
  # (SET TIME ZONE does not use an equals sign like other SET variables)
  if ActiveRecord::Base.default_timezone == :utc
    execute("SET time zone 'UTC'", 'SCHEMA')
  elsif @local_tz
    execute("SET time zone '#{@local_tz}'", 'SCHEMA')
  end

  # SET statements from :variables config hash
  # http://www.postgresql.org/docs/8.3/static/sql-set.html
  variables = @config[:variables] || {}
  variables.map do |k, v|
    if v == ':default' || v == :default
      # Sets the value to the global or compile default
      execute("SET SESSION #{k} TO DEFAULT", 'SCHEMA')
    elsif !v.nil?
      execute("SET SESSION #{k} TO #{quote(v)}", 'SCHEMA')
    end
  end
end
connect() click to toggle source

Connects to a PostgreSQL server and sets up the adapter depending on the connected server's characteristics.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 650
def connect
  @connection = PGconn.connect(@connection_parameters)

  # Money type has a fixed precision of 10 in PostgreSQL 8.2 and below, and as of
  # PostgreSQL 8.3 it has a fixed precision of 19. PostgreSQLColumn.extract_precision
  # should know about this but can't detect it there, so deal with it here.
  OID::Money.precision = (postgresql_version >= 80300) ? 19 : 10

  configure_connection
rescue ::PG::Error => error
  if error.message.include?("does not exist")
    raise ActiveRecord::NoDatabaseError.new(error.message, error)
  else
    raise
  end
end
exec_cache(sql, name, binds) click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 595
def exec_cache(sql, name, binds)
  stmt_key = prepare_statement(sql)
  type_casted_binds = binds.map { |col, val|
    [col, type_cast(val, col)]
  }

  log(sql, name, type_casted_binds, stmt_key) do
    @connection.exec_prepared(stmt_key, type_casted_binds.map { |_, val| val })
  end
rescue ActiveRecord::StatementInvalid => e
  pgerror = e.original_exception

  # Get the PG code for the failure.  Annoyingly, the code for
  # prepared statements whose return value may have changed is
  # FEATURE_NOT_SUPPORTED.  Check here for more details:
  # http://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/backend/utils/cache/plancache.c#l573
  begin
    code = pgerror.result.result_error_field(PGresult::PG_DIAG_SQLSTATE)
  rescue
    raise e
  end
  if FEATURE_NOT_SUPPORTED == code
    @statements.delete sql_key(sql)
    retry
  else
    raise e
  end
end
exec_no_cache(sql, name, binds) click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 591
def exec_no_cache(sql, name, binds)
  log(sql, name, binds) { @connection.async_exec(sql, []) }
end
execute_and_clear(sql, name, binds) { |result| ... } click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 583
def execute_and_clear(sql, name, binds)
  result = without_prepared_statement?(binds) ? exec_no_cache(sql, name, binds) :
                                                exec_cache(sql, name, binds)
  ret = yield result
  result.clear
  ret
end
last_insert_id_value(sequence_name) click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 706
def last_insert_id_value(sequence_name)
  last_insert_id_result(sequence_name).rows.first.first
end
prepare_statement(sql) click to toggle source

Prepare the statement if it hasn't been prepared, return the statement key.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 632
def prepare_statement(sql)
  sql_key = sql_key(sql)
  unless @statements.key? sql_key
    nextkey = @statements.next_key
    begin
      @connection.prepare nextkey, sql
    rescue => e
      raise translate_exception_class(e, sql)
    end
    # Clear the queue
    @connection.get_last_result
    @statements[sql_key] = nextkey
  end
  @statements[sql_key]
end
sql_key(sql) click to toggle source

Returns the statement identifier for the client side cache of statements

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 626
def sql_key(sql)
  "#{schema_search_path}-#{sql}"
end