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ActiveRecord::ConnectionAdapters::PostgreSQLAdapter

The PostgreSQL adapter works both with the native C (ruby.scripting.ca/postgres/) and the pure Ruby (available both as gem and from rubyforge.org/frs/?group_id=234&release_id=1944) drivers.

Options:

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 312
def initialize(connection, logger, connection_parameters, config)
  super(connection, logger)

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

  connection_parameters.delete :prepared_statements

  @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,
                                  config.fetch(:statement_limit) { 1000 }

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

  @local_tz = execute('SHOW TIME ZONE', 'SCHEMA').first["TimeZone"]
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 346
def active?
  @connection.query 'SELECT 1'
  true
rescue PGError
  false
end
adapter_name() click to toggle source

Returns 'PostgreSQL' as adapter name for identification purposes.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 241
def adapter_name
  ADAPTER_NAME
end
add_column(table_name, column_name, type, options = {}) click to toggle source

Adds a new column to the named table. See TableDefinition#column for details of the options you can use.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 1025
def add_column(table_name, column_name, type, options = {})
  clear_cache!
  add_column_sql = "ALTER TABLE #{quote_table_name(table_name)} ADD COLUMN #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
  add_column_options!(add_column_sql, options)

  execute add_column_sql
end
begin_db_transaction() click to toggle source

Begins a transaction.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 702
def begin_db_transaction
  execute "BEGIN"
end
change_column(table_name, column_name, type, options = {}) click to toggle source

Changes the column of a table.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 1034
def change_column(table_name, column_name, type, options = {})
  clear_cache!
  quoted_table_name = quote_table_name(table_name)

  execute "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quote_column_name(column_name)} TYPE #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"

  change_column_default(table_name, column_name, options[:default]) if options_include_default?(options)
  change_column_null(table_name, column_name, options[:null], options[:default]) if options.key?(:null)
end
change_column_default(table_name, column_name, default) click to toggle source

Changes the default value of a table column.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 1045
def change_column_default(table_name, column_name, default)
  clear_cache!
  execute "ALTER TABLE #{quote_table_name(table_name)} ALTER COLUMN #{quote_column_name(column_name)} SET DEFAULT #{quote(default)}"
end
change_column_null(table_name, column_name, null, default = nil) click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 1050
def change_column_null(table_name, column_name, null, default = nil)
  clear_cache!
  unless null || default.nil?
    execute("UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote(default)} WHERE #{quote_column_name(column_name)} IS NULL")
  end
  execute("ALTER TABLE #{quote_table_name(table_name)} ALTER #{quote_column_name(column_name)} #{null ? 'DROP' : 'SET'} NOT NULL")
end
clear_cache!() click to toggle source

Clears the prepared statements cache.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 341
def clear_cache!
  @statements.clear
end
client_min_messages() click to toggle source

Returns the current client message level.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 900
def client_min_messages
  query('SHOW client_min_messages', 'SCHEMA')[0][0]
end
client_min_messages=(level) click to toggle source

Set the client message level.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 905
def client_min_messages=(level)
  execute("SET client_min_messages TO '#{level}'", 'SCHEMA')
end
columns(table_name, name = nil) click to toggle source

Returns the list of all column definitions for a table.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 857
def columns(table_name, name = nil)
  # Limit, precision, and scale are all handled by the superclass.
  column_definitions(table_name).collect do |column_name, type, default, notnull|
    PostgreSQLColumn.new(column_name, default, type, notnull == 'f')
  end
end
commit_db_transaction() click to toggle source

Commits a transaction.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 707
def commit_db_transaction
  execute "COMMIT"
end
create_database(name, options = {}) click to toggle source

Create a new PostgreSQL database. Options include :owner, :template, :encoding, :tablespace, and :connection_limit (note that MySQL uses :charset while PostgreSQL uses :encoding).

Example:

create_database config[:database], config
create_database 'foo_development', :encoding => 'unicode'
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 748
def create_database(name, options = {})
  options = options.reverse_merge(:encoding => "utf8")

  option_string = options.symbolize_keys.sum do |key, value|
    case key
    when :owner
      " OWNER = \"#{value}\""
    when :template
      " TEMPLATE = \"#{value}\""
    when :encoding
      " ENCODING = '#{value}'"
    when :tablespace
      " TABLESPACE = \"#{value}\""
    when :connection_limit
      " CONNECTION LIMIT = #{value}"
    else
      ""
    end
  end

  execute "CREATE DATABASE #{quote_table_name(name)}#{option_string}"
end
create_savepoint() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 720
def create_savepoint
  execute("SAVEPOINT #{current_savepoint_name}")
end
current_database() click to toggle source

Returns the current database name.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 865
def current_database
  query('select current_database()')[0][0]
end
current_schema() click to toggle source

Returns the current schema name.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 870
def current_schema
  query('SELECT current_schema', 'SCHEMA')[0][0]
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 367
def disconnect!
  clear_cache!
  @connection.close rescue nil
end
encoding() click to toggle source

Returns the current database encoding format.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 875
def encoding
  query(          SELECT pg_encoding_to_char(pg_database.encoding) FROM pg_database          WHERE pg_database.datname LIKE '#{current_database}')[0][0]
end
escape_bytea(value) click to toggle source

Escapes binary strings for bytea input to the database.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 420
def escape_bytea(value)
  @connection.escape_bytea(value) if value
end
exec_delete(sql, name = 'SQL', binds = []) click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 673
def exec_delete(sql, name = 'SQL', binds = [])
  log(sql, name, binds) do
    result = binds.empty? ? exec_no_cache(sql, binds) :
                            exec_cache(sql, binds)
    affected = result.cmd_tuples
    result.clear
    affected
  end
end
Also aliased as: exec_update
exec_query(sql, name = 'SQL', binds = []) click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 662
def exec_query(sql, name = 'SQL', binds = [])
  log(sql, name, binds) do
    result = binds.empty? ? exec_no_cache(sql, binds) :
                            exec_cache(sql, binds)

    ret = ActiveRecord::Result.new(result.fields, result_as_array(result))
    result.clear
    return ret
  end
end
exec_update(sql, name = 'SQL', binds = []) click to toggle source
Alias for: exec_delete
execute(sql, name = nil) click to toggle source

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

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 652
def execute(sql, name = nil)
  log(sql, name) do
    @connection.async_exec(sql)
  end
end
explain(arel, binds = []) click to toggle source

DATABASE STATEMENTS ======================================

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 536
def explain(arel, binds = [])
  sql = "EXPLAIN #{to_sql(arel, binds)}"
  ExplainPrettyPrinter.new.pp(exec_query(sql, 'EXPLAIN', binds))
end
index_name_length() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 1072
def index_name_length
  63
end
indexes(table_name, name = nil) click to toggle source

Returns an array of indexes for the given table.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 818
def indexes(table_name, name = nil)
   result = query(           SELECT distinct i.relname, d.indisunique, d.indkey, pg_get_indexdef(d.indexrelid), t.oid           FROM pg_class t           INNER JOIN pg_index d ON t.oid = d.indrelid           INNER JOIN pg_class i ON d.indexrelid = i.oid           WHERE i.relkind = 'i'             AND d.indisprimary = 'f'             AND t.relname = '#{table_name}'             AND i.relnamespace IN (SELECT oid FROM pg_namespace WHERE nspname = ANY (current_schemas(false)) )          ORDER BY i.relname, name)


  result.map do |row|
    index_name = row[0]
    unique = row[1] == 't'
    indkey = row[2].split(" ")
    inddef = row[3]
    oid = row[4]

    columns = Hash[query(          SELECT a.attnum, a.attname          FROM pg_attribute a          WHERE a.attrelid = #{oid}          AND a.attnum IN (#{indkey.join(",")}), "Columns for index #{row[0]} on #{table_name}")]

    column_names = columns.values_at(*indkey).compact

    # add info on sort order for columns (only desc order is explicitly specified, asc is the default)
    desc_order_columns = inddef.scan(/(\w+) DESC/).flatten
    orders = desc_order_columns.any? ? Hash[desc_order_columns.map {|order_column| [order_column, :desc]}] : {}

    column_names.empty? ? nil : IndexDefinition.new(table_name, index_name, unique, column_names, [], orders)
  end.compact
end
insert_sql(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil) click to toggle source

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

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 585
def insert_sql(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
  unless pk
    # Extract the table from the insert sql. Yuck.
    table_ref = extract_table_ref_from_insert_sql(sql)
    pk = primary_key(table_ref) if table_ref
  end

  if pk
    select_value("#{sql} RETURNING #{quote_column_name(pk)}")
  else
    super
  end
end
outside_transaction?() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 716
def outside_transaction?
  @connection.transaction_status == PGconn::PQTRANS_IDLE
end
primary_key(table) click to toggle source

Returns just a table's primary key

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 994
def primary_key(table)
  row = exec_query(          SELECT DISTINCT(attr.attname)          FROM pg_attribute attr          INNER JOIN pg_depend dep ON attr.attrelid = dep.refobjid AND attr.attnum = dep.refobjsubid          INNER JOIN pg_constraint cons ON attr.attrelid = cons.conrelid AND attr.attnum = cons.conkey[1]          WHERE cons.contype = 'p'            AND dep.refobjid = $1::regclass, 'SCHEMA', [[nil, table]]).rows.first

  row && row.first
end
quote_table_name(name) click to toggle source

Checks the following cases:

  • table_name

  • "table.name"

  • schema_name.table_name

  • schema_name."table.name"

  • "schema.name".table_name

  • "schema.name"."table.name"

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 485
def quote_table_name(name)
  schema, name_part = extract_pg_identifier_from_name(name.to_s)

  unless name_part
    quote_column_name(schema)
  else
    table_name, name_part = extract_pg_identifier_from_name(name_part)
    "#{quote_column_name(schema)}.#{quote_column_name(table_name)}"
  end
end
reconnect!() click to toggle source

Close then reopen the connection.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 354
def reconnect!
  clear_cache!
  @connection.reset
  configure_connection
end
release_savepoint() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 728
def release_savepoint
  execute("RELEASE SAVEPOINT #{current_savepoint_name}")
end
rename_column(table_name, column_name, new_column_name) click to toggle source

Renames a column in a table.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 1059
def rename_column(table_name, column_name, new_column_name)
  clear_cache!
  execute "ALTER TABLE #{quote_table_name(table_name)} RENAME COLUMN #{quote_column_name(column_name)} TO #{quote_column_name(new_column_name)}"
end
rename_index(table_name, old_name, new_name) click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 1068
def rename_index(table_name, old_name, new_name)
  execute "ALTER INDEX #{quote_column_name(old_name)} RENAME TO #{quote_table_name(new_name)}"
end
rename_table(name, new_name) click to toggle source

Renames a table. Also renames a table's primary key sequence if the sequence name matches the Active Record default.

Example:

rename_table('octopuses', 'octopi')
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 1013
def rename_table(name, new_name)
  clear_cache!
  execute "ALTER TABLE #{quote_table_name(name)} RENAME TO #{quote_table_name(new_name)}"
  pk, seq = pk_and_sequence_for(new_name)
  if seq == "#{name}_#{pk}_seq"
    new_seq = "#{new_name}_#{pk}_seq"
    execute "ALTER TABLE #{quote_table_name(seq)} RENAME TO #{quote_table_name(new_seq)}"
  end
end
reset!() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 360
def reset!
  clear_cache!
  super
end
rollback_db_transaction() click to toggle source

Aborts a transaction.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 712
def rollback_db_transaction
  execute "ROLLBACK"
end
rollback_to_savepoint() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 724
def rollback_to_savepoint
  execute("ROLLBACK TO SAVEPOINT #{current_savepoint_name}")
end
schema_exists?(name) click to toggle source

Returns true if schema exists.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 809
def schema_exists?(name)
  exec_query(          SELECT COUNT(*)          FROM pg_namespace          WHERE nspname = $1, 'SCHEMA', [[nil, name]]).rows.first[0].to_i > 0
end
schema_search_path() click to toggle source

Returns the active schema search path.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 895
def schema_search_path
  @schema_search_path ||= query('SHOW search_path', 'SCHEMA')[0][0]
end
schema_search_path=(schema_csv) click to toggle source

Sets the schema search path to a string of comma-separated schema names. Names beginning with $ have to be quoted (e.g. $user => '$user'). See: www.postgresql.org/docs/current/static/ddl-schemas.html

This should be not be called manually but set in database.yml.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 887
def schema_search_path=(schema_csv)
  if schema_csv
    execute("SET search_path TO #{schema_csv}", 'SCHEMA')
    @schema_search_path = schema_csv
  end
end
select_rows(sql, name = nil) click to toggle source

Executes a SELECT query and returns an array of rows. Each row is an array of field values.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 580
def select_rows(sql, name = nil)
  select_raw(sql, name).last
end
serial_sequence(table, column) click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 916
def serial_sequence(table, column)
  result = exec_query(          SELECT pg_get_serial_sequence($1, $2), 'SCHEMA', [[nil, table], [nil, column]])
  result.rows.first.first
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 512
def session_auth=(user)
  clear_cache!
  exec_query "SET SESSION AUTHORIZATION #{user}"
end
set_standard_conforming_strings() click to toggle source

Enable standard-conforming strings if available.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 387
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
sql_for_insert(sql, pk, id_value, sequence_name, binds) click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 684
def sql_for_insert(sql, pk, id_value, sequence_name, binds)
  unless pk
    # Extract the table from the insert sql. Yuck.
    table_ref = extract_table_ref_from_insert_sql(sql)
    pk = primary_key(table_ref) if table_ref
  end

  sql = "#{sql} RETURNING #{quote_column_name(pk)}" if pk

  [sql, binds]
end
substitute_at(column, index) click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 658
def substitute_at(column, index)
  Arel::Nodes::BindParam.new "$#{index + 1}"
end
supports_ddl_transactions?() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 398
def supports_ddl_transactions?
  true
end
supports_explain?() click to toggle source

Returns true.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 408
def supports_explain?
  true
end
supports_index_sort_order?() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 251
def supports_index_sort_order?
  true
end
supports_insert_with_returning?() click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 394
def supports_insert_with_returning?
  true
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 377
def supports_migrations?
  true
end
supports_savepoints?() click to toggle source

Returns true, since this connection adapter supports savepoints.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 403
def supports_savepoints?
  true
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 247
def supports_statement_cache?
  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 413
def table_alias_length
  @table_alias_length ||= query('SHOW max_identifier_length')[0][0].to_i
end
table_exists?(name) click to toggle source

Returns true if table exists. If the schema is not specified as part of name then it will only find tables within the current schema search path (regardless of permissions to access tables in other schemas)

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 791
def table_exists?(name)
  schema, table = Utils.extract_schema_and_table(name.to_s)
  return false unless table

  binds = [[nil, table]]
  binds << [nil, schema] if schema

  exec_query(            SELECT COUNT(*)            FROM pg_class c            LEFT JOIN pg_namespace n ON n.oid = c.relnamespace            WHERE c.relkind in ('v','r')            AND c.relname = $1            AND n.nspname = #{schema ? '$2' : 'ANY (current_schemas(false))'}, 'SCHEMA', binds).rows.first[0].to_i > 0
end
tables(name = nil) click to toggle source

Returns the list of all tables in the schema search path or a specified schema.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 780
def tables(name = nil)
  query(          SELECT tablename          FROM pg_tables          WHERE schemaname = ANY (current_schemas(false)), 'SCHEMA').map { |row| row[0] }
end
type_cast(value, column) click to toggle source
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 460
def type_cast(value, column)
  return super unless column

  case value
  when String
    return super unless 'bytea' == column.sql_type
    { :value => value, :format => 1 }
  else
    super
  end
end
type_to_sql(type, limit = nil, precision = nil, scale = nil) click to toggle source

Maps logical Rails types to PostgreSQL-specific data types.

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 1077
def type_to_sql(type, limit = nil, precision = nil, scale = nil)
  case type.to_s
  when 'binary'
    # PostgreSQL doesn't support limits on binary (bytea) columns.
    # The hard limit is 1Gb, because of a 32-bit size field, and TOAST.
    case limit
    when nil, 0..0x3fffffff; super(type)
    else raise(ActiveRecordError, "No binary type has byte size #{limit}.")
    end
  when 'integer'
    return 'integer' unless limit
  
    case limit
      when 1, 2; 'smallint'
      when 3, 4; 'integer'
      when 5..8; 'bigint'
      else raise(ActiveRecordError, "No integer type has byte size #{limit}. Use a numeric with precision 0 instead.")
    end
  else
    super
  end
end
unescape_bytea(value) click to toggle source

Unescapes bytea output from a database to the binary string it represents. NOTE: This is NOT an inverse of escape_bytea! This is only to be used

on escaped binary output from database drive.
# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 427
def unescape_bytea(value)
  @connection.unescape_bytea(value) if value
end
update_sql(sql, name = nil) click to toggle source

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

# File lib/active_record/connection_adapters/postgresql_adapter.rb, line 697
def update_sql(sql, name = nil)
  super.cmd_tuples
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 1139
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 1143
def translate_exception(exception, message)
  case exception.message
  when /duplicate key value violates unique constraint/
    RecordNotUnique.new(message, exception)
  when /violates foreign key constraint/
    InvalidForeignKey.new(message, exception)
  else
    super
  end
end

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