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Class: ActiveRecord::ConnectionAdapters::PostgreSQLAdapter

Overview

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/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 .

Constant Summary

::ActiveSupport::Callbacks - Included

CALLBACK_FILTER_TYPES

AbstractAdapter - Inherited

ADAPTER_NAME, SIMPLE_INT

Class Method Summary

AbstractAdapter - Inherited

::ActiveSupport::DescendantsTracker - Inherited

clear, descendants, direct_descendants,
store_inherited

This is the only method that is not thread safe, but is only ever called during the eager loading phase.

Instance Attribute Summary

PostgreSQL::SchemaStatements - Included

#client_min_messages

Returns the current client message level.

#client_min_messages=

Set the client message level.

#schema_search_path

Returns the active schema search path.

#schema_search_path=

Sets the schema search path to a string of comma-separated schema names.

AbstractAdapter - Inherited

#active?

Checks whether the connection to the database is still active.

#in_use?
#logger, #owner, #pool, #prepared_statements,
#requires_reloading?

Returns true if its required to reload the connection between requests for development mode.

#schema_cache, #schema_cache=, #supports_bulk_alter?,
#supports_ddl_transactions?

Does this adapter support DDL rollbacks in transactions? That is, would CREATE TABLE or ALTER TABLE get rolled back by a transaction?

#supports_explain?

Does this adapter support explain?

#supports_extensions?

Does this adapter support database extensions?

#supports_foreign_keys?

Does this adapter support creating foreign key constraints?

#supports_index_sort_order?

Does this adapter support index sort order?

#supports_indexes_in_create?

Does this adapter support creating indexes in the same statement as creating the table?

#supports_migrations?

Does this adapter support migrations?

#supports_partial_index?

Does this adapter support partial indices?

#supports_primary_key?

Can this adapter determine the primary key for tables not attached to an Active Record class, such as join tables?

#supports_savepoints?

Does this adapter support savepoints?

#supports_transaction_isolation?

Does this adapter support setting the isolation level for a transaction?

#supports_views?

Does this adapter support views?

#visitor

DatabaseStatements - Included

#begin_transaction, #commit_transaction, #current_transaction, #open_transactions, #rollback_transaction,
#supports_statement_cache?

Returns true when the connection adapter supports prepared statement caching, otherwise returns false

#transaction_open?, #within_new_transaction

Instance Method Summary

PostgreSQL::DatabaseStatements - Included

#begin_db_transaction

Begins a transaction.

#begin_isolated_db_transaction,
#commit_db_transaction

Commits a transaction.

#create, #exec_delete, #exec_insert, #exec_query,
#exec_rollback_db_transaction

Aborts a transaction.

#exec_update
#execute

Executes an SQL statement, returning a PGresult object on success or raising a PGError exception otherwise.

#explain,
#insert_sql

Executes an INSERT query and returns the new record's ID.

#select_rows

Executes a SELECT query and returns an array of rows.

#select_value, #select_values, #sql_for_insert,
#update_sql

Executes an UPDATE query and returns the number of affected tuples.

PostgreSQL::SchemaStatements - Included

#change_column

Changes the column of a table.

#change_column_default

Changes the default value of a table column.

#change_column_null,
#collation

Returns the current database collation.

#columns

Returns the list of all column definitions for a table.

#create_database

Create a new PostgreSQL database.

#create_schema

Creates a schema for the given schema name.

#ctype

Returns the current database ctype.

#current_database

Returns the current database name.

#current_schema

Returns the current schema name.

#data_source_exists?
#data_sources

:nodoc.

#drop_schema

Drops the schema for the given schema name.

#drop_table,
#encoding

Returns the current database encoding format.

#foreign_keys, #index_name_exists?, #index_name_length,
#indexes

Returns an array of indexes for the given table.

#primary_key

Returns just a table's primary key.

#rename_index,
#rename_table

Renames a table.

#schema_exists?

Returns true if schema exists.

#schema_names

Returns an array of schema names.

#serial_sequence,
#table_exists?

Returns true if table exists.

#tables

Returns the list of all tables in the schema search path.

#type_to_sql

Maps logical ::Rails types to PostgreSQL-specific data types.

PostgreSQL::Quoting - Included

#escape_bytea

Escapes binary strings for bytea input to the database.

#quote_table_name

Checks the following cases:

#quote_table_name_for_assignment,
#unescape_bytea

Unescapes bytea output from a database to the binary string it represents.

AbstractAdapter - Inherited

#adapter_name

Returns the human-readable name of the adapter.

#case_insensitive_comparison, #case_sensitive_comparison, #case_sensitive_modifier,
#clear_cache!

Clear any caching the database adapter may be doing, for example clearing the prepared statement cache.

#close

Check the connection back in to the connection pool.

#collector, #create_savepoint, #current_savepoint_name,
#disable_extension

This is meant to be implemented by the adapters that support extensions.

#disable_referential_integrity

Override to turn off referential integrity while executing &block.

#disconnect!

Disconnects from the database if already connected.

#enable_extension

This is meant to be implemented by the adapters that support extensions.

#expire,
#extensions

A list of extensions, to be filled in by adapters that support them.

#index_algorithms

A list of index algorithms, to be filled by adapters that support them.

#lease, #new_column,
#prefetch_primary_key?

Should primary key values be selected from their corresponding sequence before the insert statement? If true, next_sequence_value is called before each insert to set the record's primary key.

#raw_connection

Provides access to the underlying database driver for this adapter.

#reconnect!

Disconnects from the database if already connected, and establishes a new connection with the database.

#release_savepoint,
#reset!

Reset the state of this connection, directing the DBMS to clear transactions and other connection-related server-side state.

#schema_creation,
#substitute_at

Returns a bind substitution value given a bind column NOTE: The column param is currently being used by the sqlserver-adapter.

#unprepared_statement, #valid_type?,
#verify!

Checks whether the connection to the database is still active (i.e. not stale).

ColumnDumper - Included

#column_spec,
#migration_keys

Lists the valid migration options.

#prepare_column_options

This can be overridden on a Adapter level basis to support other extended datatypes (Example: Adding an array option in the PostgreSQLAdapter).

::ActiveSupport::Callbacks - Included

#run_callbacks

Runs the callbacks for the given event.

::ActiveRecord::QueryCache - Included

DatabaseLimits - Included

#allowed_index_name_length

Returns the maximum allowed length for an index name.

#column_name_length

Returns the maximum length of a column name.

#columns_per_multicolumn_index

Returns the maximum number of columns in a multicolumn index.

#columns_per_table

Returns the maximum number of columns per table.

#in_clause_length

Returns the maximum number of elements in an IN (x,y,z) clause.

#index_name_length

Returns the maximum length of an index name.

#indexes_per_table

Returns the maximum number of indexes per table.

#joins_per_query

Returns maximum number of joins in a single query.

#sql_query_length

Returns the maximum length of an SQL query.

#table_alias_length

Returns the maximum length of a table alias.

#table_name_length

Returns the maximum length of a table name.

Quoting - Included

#quote

Quotes the column value to help prevent SQL injection attacks.

#quote_column_name

Quotes the column name.

#quote_string

Quotes a string, escaping any ' (single quote) and \ (backslash) characters.

#quote_table_name

Quotes the table name.

#quote_table_name_for_assignment

Override to return the quoted table name for assignment.

#quoted_date, #quoted_false, #quoted_true,
#type_cast

Cast a value to a type that the database understands.

#unquoted_false, #unquoted_true

DatabaseStatements - Included

#add_transaction_record

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

#begin_db_transaction

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

#begin_isolated_db_transaction

Begins the transaction with the isolation level set.

#commit_db_transaction

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

#default_sequence_name,
#delete

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

#empty_insert_statement_value,
#exec_delete

Executes delete sql statement in the context of this connection using binds as the bind substitutes.

#exec_insert

Executes insert sql statement in the context of this connection using binds as the bind substitutes.

#exec_query

Executes sql statement in the context of this connection using binds as the bind substitutes.

#exec_update

Executes update sql statement in the context of this connection using binds as the bind substitutes.

#execute

Executes the SQL statement in the context of this connection.

#initialize,
#insert

Returns the last auto-generated ID from the affected table.

#insert_fixture

Inserts the given fixture into the table.

#reset_sequence!

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

#rollback_db_transaction

Rolls back the transaction (and turns on auto-committing).

#rollback_to_savepoint,
#sanitize_limit

Sanitizes the given LIMIT parameter in order to prevent SQL injection.

#select_all

Returns an ::ActiveRecord::Result instance.

#select_one

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

#select_rows

Returns an array of arrays containing the field values.

#select_value

Returns a single value from a record.

#select_values

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

#to_sql

Converts an arel AST to SQL.

#transaction

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

#transaction_isolation_levels, #transaction_state,
#truncate

Executes the truncate statement.

#update

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

SchemaStatements - Included

#add_belongs_to
#add_column

Adds a new column to the named table.

#add_foreign_key

Adds a new foreign key.

#add_index

Adds a new index to the table.

#add_reference

Adds a reference.

#add_timestamps

Adds timestamps (created_at and updated_at) columns to table_name.

#assume_migrated_upto_version,
#change_column

Changes the column's definition according to the new options.

#change_column_default

Sets a new default value for a column:

#change_column_null

Sets or removes a NOT NULL constraint on a column.

#change_table

A block for changing columns in table.

#column_exists?

Checks to see if a column exists in a given table.

#columns

Returns an array of Column objects for the table specified by table_name.

#create_join_table

Creates a new join table with the name created using the lexical order of the first two arguments.

#create_table

Creates a new table with the name table_name.

#data_source_exists?

Checks to see if the data source name exists on the database.

#data_sources

Returns the relation names useable to back Active Record models.

#drop_join_table

Drops the join table specified by the given arguments.

#drop_table

Drops a table from the database.

#foreign_keys

Returns an array of foreign keys for the given table.

#index_exists?

Checks to see if an index exists on a table for a given index definition.

#index_name_exists?

Verifies the existence of an index with a given name.

#initialize_schema_migrations_table

Should not be called normally, but this operation is non-destructive.

#native_database_types

Returns a hash of mappings from the abstract data types to the native database types.

#remove_belongs_to
#remove_column

Removes the column from the table definition.

#remove_columns

Removes the given columns from the table definition.

#remove_foreign_key

Removes the given foreign key from the table.

#remove_index

Removes the given index from the table.

#remove_reference

Removes the reference(s).

#remove_timestamps

Removes the timestamp columns (created_at and updated_at) from the table definition.

#rename_column

Renames a column.

#rename_index

Renames an index.

#rename_table

Renames a table.

#table_alias_for

Truncates a table alias according to the limits of the current adapter.

#table_exists?

Checks to see if the table table_name exists on the database.

Constructor Details

.new(connection, logger, connection_parameters, config) ⇒ PostgreSQLAdapter

Initializes and connects a PostgreSQL adapter.

[ GitHub ]

  
# File 'activerecord/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

Instance Attribute Details

#active?Boolean (readonly)

Is this connection alive and ready for queries?

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 266

def active?
  @connection.query 'SELECT 1'
  true
rescue PGError
  false
end

#session_auth=(user) (writeonly)

Set the authorized user for this session

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 371

def session_auth=(user)
  clear_cache!
  exec_query "SET SESSION AUTHORIZATION #{user}"
end

#supports_ddl_transactions?Boolean (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 315

def supports_ddl_transactions?
  true
end

#supports_explain?Boolean (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 319

def supports_explain?
  true
end

#supports_extensions?Boolean (readonly)

Returns true if pg > 9.1

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 324

def supports_extensions?
  postgresql_version >= 90100
end

#supports_foreign_keys?Boolean (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 160

def supports_foreign_keys?
  true
end

#supports_index_sort_order?Boolean (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 148

def supports_index_sort_order?
  true
end

#supports_materialized_views?Boolean (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 333

def supports_materialized_views?
  postgresql_version >= 90300
end

#supports_migrations?Boolean (readonly)

Returns true, since this connection adapter supports migrations.

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 302

def supports_migrations?
  true
end

#supports_partial_index?Boolean (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 152

def supports_partial_index?
  true
end

#supports_ranges?Boolean (readonly)

::Range datatypes weren't introduced until PostgreSQL 9.2

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 329

def supports_ranges?
  postgresql_version >= 90200
end

#supports_statement_cache?Boolean (readonly)

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

[ GitHub ]

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

def supports_statement_cache?
  true
end

#supports_transaction_isolation?Boolean (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 156

def supports_transaction_isolation?
  true
end

#supports_views?Boolean (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 164

def supports_views?
  true
end

#use_insert_returning?Boolean (readonly)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 376

def use_insert_returning?
  @use_insert_returning
end

Instance Method Details

#clear_cache!

Clears the prepared statements cache.

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 257

def clear_cache!
  @statements.clear
end

#disable_extension(name)

[ GitHub ]

  
# File 'activerecord/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!

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 292

def disconnect!
  super
  @connection.close rescue nil
end

#enable_extension(name)

[ GitHub ]

  
# File 'activerecord/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) ⇒ Boolean

[ GitHub ]

  
# File 'activerecord/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

[ GitHub ]

  
# File 'activerecord/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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 168

def index_algorithms
  { concurrently: 'CONCURRENTLY' }
end

#migration_keys

Adds :array as a valid migration key

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 138

def migration_keys
  super + [:array]
end

#reconnect!

Close then reopen the connection.

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 274

def reconnect!
  super
  @connection.reset
  configure_connection
end

#reset!

[ GitHub ]

  
# File 'activerecord/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

#set_standard_conforming_strings

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 311

def set_standard_conforming_strings
  execute('SET standard_conforming_strings = on', 'SCHEMA')
end

#table_alias_length

Returns the configured supported identifier length supported by PostgreSQL

[ GitHub ]

  
# File 'activerecord/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)

[ GitHub ]

  
# File 'activerecord/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

#valid_type?(type) ⇒ Boolean

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb', line 380

def valid_type?(type)
  !native_database_types[type].nil?
end