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class ActiveRecord::ConnectionAdapters::PostgreSQLAdapter

Parent:: ActiveRecord::ConnectionAdapters::AbstractAdapter
Included modules:: ActiveRecord::ConnectionAdapters::PostgreSQL::Quoting, ActiveRecord::ConnectionAdapters::PostgreSQL::SchemaStatements, ActiveRecord::ConnectionAdapters::PostgreSQL::DatabaseStatements, ActiveRecord::ConnectionAdapters::PostgreSQL::ColumnDumper

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 of RETURNING for INSERT statements defaults to true.

Any further options are used as connection parameters to libpq. See www.postgresql.org/docs/current/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/current/static/libpq-envars.html .

Constants

ADAPTER_NAME

CACHED_PLAN_HEURISTIC

Annoyingly, the code for prepared statements whose return value may have changed is FEATURE_NOT_SUPPORTED.

This covers various different error types so we need to do additional work to classify the exception definitively as a ActiveRecord::PreparedStatementCacheExpired

Check here for more details: git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/backend/utils/cache/plancache.c#l573

FOREIGN_KEY_VIOLATION

NATIVE_DATABASE_TYPES

UNIQUE_VIOLATION

VALUE_LIMIT_VIOLATION

See www.postgresql.org/docs/current/static/errcodes-appendix.html

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 208
def initialize(connection, logger, connection_parameters, config)
  super(connection, logger, config)

  @connection_parameters = connection_parameters

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

  connect
  add_pg_encoders
  @statements = StatementPool.new @connection,
                                  self.class.type_cast_config_to_integer(config[:statement_limit])

  if postgresql_version < 90100
    raise "Your version of PostgreSQL (#{postgresql_version}) is too old. Active Record supports PostgreSQL >= 9.1."
  end

  add_pg_decoders

  @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?() Show source

Is this connection alive and ready for queries?

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 244
def active?
  @connection.query 'SELECT 1'
  true
rescue PGError
  false
end

clear_cache!() Show source

Clears the prepared statements cache.

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 235
def clear_cache!
  @statements.clear
end

disable_extension(name) Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 338
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 270
def disconnect!
  super
  @connection.close rescue nil
end

enable_extension(name) Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 332
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 344
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() Show source

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

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 352
def extensions
  if supports_extensions?
    exec_query("SELECT extname from pg_extension", "SCHEMA").cast_values
  else
    super
  end
end

index_algorithms() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 175
def index_algorithms
  { concurrently: 'CONCURRENTLY' }
end

postgresql_version() Show source

Returns the version of the connected PostgreSQL server.

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 399
def postgresql_version
  @connection.server_version
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 252
def reconnect!
  super
  @connection.reset
  configure_connection
end

reset!() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 258
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) Show source

Set the authorized user for this session

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 366
def session_auth=(user)
  clear_cache!
  exec_query "SET SESSION AUTHORIZATION #{user}"
end

set_standard_conforming_strings() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 289
def set_standard_conforming_strings
  execute('SET standard_conforming_strings = on', 'SCHEMA')
end

supports_advisory_locks?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 297
def supports_advisory_locks?
  true
end

supports_comments?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 167
def supports_comments?
  true
end

supports_datetime_with_precision?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 159
def supports_datetime_with_precision?
  true
end

supports_ddl_transactions?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 293
def supports_ddl_transactions?
  true
end

supports_explain?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 301
def supports_explain?
  true
end

supports_expression_index?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 143
def supports_expression_index?
  true
end

supports_extensions?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 305
def supports_extensions?
  true
end

supports_foreign_keys?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 151
def supports_foreign_keys?
  true
end

supports_index_sort_order?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 135
def supports_index_sort_order?
  true
end

supports_json?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 163
def supports_json?
  postgresql_version >= 90200
end

supports_materialized_views?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 314
def supports_materialized_views?
  postgresql_version >= 90300
end

supports_migrations?() Show source

Returns true, since this connection adapter supports migrations.

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 280
def supports_migrations?
  true
end

supports_partial_index?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 139
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 310
def supports_ranges?
  postgresql_version >= 90200
end

supports_savepoints?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 171
def supports_savepoints?
  true
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 131
def supports_statement_cache?
  true
end

supports_transaction_isolation?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 147
def supports_transaction_isolation?
  true
end

supports_views?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 155
def supports_views?
  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 361
def table_alias_length
  @table_alias_length ||= query('SHOW max_identifier_length', 'SCHEMA')[0][0].to_i
end

truncate(table_name, name = nil) Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 239
def truncate(table_name, name = nil)
  exec_query "TRUNCATE TABLE #{quote_table_name(table_name)}", name, []
end

use_insert_returning?() Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 371
def use_insert_returning?
  @use_insert_returning
end

valid_type?(type) Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 375
def valid_type?(type)
  !native_database_types[type].nil?
end

Protected Instance Methods

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 410
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)
  when FOREIGN_KEY_VIOLATION
    InvalidForeignKey.new(message)
  when VALUE_LIMIT_VIOLATION
    ValueTooLong.new(message)
  else
    super
  end
end