require 'active_record/connection_adapters/abstract_adapter'
require 'active_support/core_ext/kernel/requires'
require 'active_support/core_ext/object/blank'
require 'pg'
module ActiveRecord
class Base
# Establishes a connection to the database that's used by all Active Record objects
def self.postgresql_connection(config) # :nodoc:
config = config.symbolize_keys
host = config[:host]
port = config[:port] || 5432
username = config[:username].to_s if config[:username]
password = config[:password].to_s if config[:password]
if config.key?(:database)
database = config[:database]
else
raise ArgumentError, "No database specified. Missing argument: database."
end
# The postgres drivers don't allow the creation of an unconnected PGconn object,
# so just pass a nil connection object for the time being.
ConnectionAdapters::PostgreSQLAdapter.new(nil, logger, [host, port, nil, nil, database, username, password], config)
end
end
module ConnectionAdapters
# PostgreSQL-specific extensions to column definitions in a table.
class PostgreSQLColumn < Column #:nodoc:
# Instantiates a new PostgreSQL column definition in a table.
def initialize(name, default, sql_type = nil, null = true)
super(name, self.class.extract_value_from_default(default), sql_type, null)
end
# :stopdoc:
class << self
attr_accessor :money_precision
end
# :startdoc:
private
def extract_limit(sql_type)
case sql_type
when /^bigint/i; 8
when /^smallint/i; 2
else super
end
end
# Extracts the scale from PostgreSQL-specific data types.
def extract_scale(sql_type)
# Money type has a fixed scale of 2.
sql_type =~ /^money/ ? 2 : super
end
# Extracts the precision from PostgreSQL-specific data types.
def extract_precision(sql_type)
if sql_type == 'money'
self.class.money_precision
else
super
end
end
# Maps PostgreSQL-specific data types to logical Rails types.
def simplified_type(field_type)
case field_type
# Numeric and monetary types
when /^(?:real|double precision)$/
:float
# Monetary types
when 'money'
:decimal
# Character types
when /^(?:character varying|bpchar)(?:\(\d+\))?$/
:string
# Binary data types
when 'bytea'
:binary
# Date/time types
when /^timestamp with(?:out)? time zone$/
:datetime
when 'interval'
:string
# Geometric types
when /^(?:point|line|lseg|box|"?path"?|polygon|circle)$/
:string
# Network address types
when /^(?:cidr|inet|macaddr)$/
:string
# Bit strings
when /^bit(?: varying)?(?:\(\d+\))?$/
:string
# XML type
when 'xml'
:xml
# Arrays
when /^\D+\[\]$/
:string
# Object identifier types
when 'oid'
:integer
# UUID type
when 'uuid'
:string
# Small and big integer types
when /^(?:small|big)int$/
:integer
# Pass through all types that are not specific to PostgreSQL.
else
super
end
end
# Extracts the value from a PostgreSQL column default definition.
def self.extract_value_from_default(default)
case default
# Numeric types
when /\A\(?(-?\d+(\.\d*)?\)?)\z/
$1
# Character types
when /\A'(.*)'::(?:character varying|bpchar|text)\z/m
$1
# Character types (8.1 formatting)
when /\AE'(.*)'::(?:character varying|bpchar|text)\z/m
$1.gsub(/\\(\d\d\d)/) { $1.oct.chr }
# Binary data types
when /\A'(.*)'::bytea\z/m
$1
# Date/time types
when /\A'(.+)'::(?:time(?:stamp)? with(?:out)? time zone|date)\z/
$1
when /\A'(.*)'::interval\z/
$1
# Boolean type
when 'true'
true
when 'false'
false
# Geometric types
when /\A'(.*)'::(?:point|line|lseg|box|"?path"?|polygon|circle)\z/
$1
# Network address types
when /\A'(.*)'::(?:cidr|inet|macaddr)\z/
$1
# Bit string types
when /\AB'(.*)'::"?bit(?: varying)?"?\z/
$1
# XML type
when /\A'(.*)'::xml\z/m
$1
# Arrays
when /\A'(.*)'::"?\D+"?\[\]\z/
$1
# Object identifier types
when /\A-?\d+\z/
$1
else
# Anything else is blank, some user type, or some function
# and we can't know the value of that, so return nil.
nil
end
end
end
# The PostgreSQL adapter works both with the native C (http://ruby.scripting.ca/postgres/) and the pure
# Ruby (available both as gem and from http://rubyforge.org/frs/?group_id=234&release_id=1944) drivers.
#
# Options:
#
# * :host - Defaults to "localhost".
# * :port - Defaults to 5432.
# * :username - Defaults to nothing.
# * :password - Defaults to nothing.
# * :database - The name of the database. No default, must be provided.
# * :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
# call on the connection.
# * :min_messages - An optional client min messages that is used in a
# SET client_min_messages TO call on the connection.
class PostgreSQLAdapter < AbstractAdapter
class TableDefinition < ActiveRecord::ConnectionAdapters::TableDefinition
def xml(*args)
options = args.extract_options!
column(args[0], 'xml', options)
end
end
ADAPTER_NAME = 'PostgreSQL'
NATIVE_DATABASE_TYPES = {
:primary_key => "serial primary key",
:string => { :name => "character varying", :limit => 255 },
:text => { :name => "text" },
:integer => { :name => "integer" },
:float => { :name => "float" },
:decimal => { :name => "decimal" },
:datetime => { :name => "timestamp" },
:timestamp => { :name => "timestamp" },
:time => { :name => "time" },
:date => { :name => "date" },
:binary => { :name => "bytea" },
:boolean => { :name => "boolean" },
:xml => { :name => "xml" }
}
# Returns 'PostgreSQL' as adapter name for identification purposes.
def adapter_name
ADAPTER_NAME
end
# Returns +true+ when the connection adapter supports prepared statement
# caching, otherwise returns +false+
def supports_statement_cache?
true
end
# Initializes and connects a PostgreSQL adapter.
def initialize(connection, logger, connection_parameters, config)
super(connection, logger)
@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
@postgresql_version = nil
@statements = {}
connect
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
def clear_cache!
@statements.each_value do |value|
@connection.query "DEALLOCATE #{value}"
end
@statements.clear
end
# Is this connection alive and ready for queries?
def active?
if @connection.respond_to?(:status)
@connection.status == PGconn::CONNECTION_OK
else
# We're asking the driver, not Active Record, so use @connection.query instead of #query
@connection.query 'SELECT 1'
true
end
# postgres-pr raises a NoMethodError when querying if no connection is available.
rescue PGError, NoMethodError
false
end
# Close then reopen the connection.
def reconnect!
if @connection.respond_to?(:reset)
clear_cache!
@connection.reset
configure_connection
else
disconnect!
connect
end
end
def reset!
clear_cache!
super
end
# Close the connection.
def disconnect!
clear_cache!
@connection.close rescue nil
end
def native_database_types #:nodoc:
NATIVE_DATABASE_TYPES
end
# Does PostgreSQL support migrations?
def supports_migrations?
true
end
# Does PostgreSQL support finding primary key on non-Active Record tables?
def supports_primary_key? #:nodoc:
true
end
# Enable standard-conforming strings if available.
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
def supports_insert_with_returning?
true
end
def supports_ddl_transactions?
true
end
def supports_savepoints?
true
end
# Returns the configured supported identifier length supported by PostgreSQL
def table_alias_length
@table_alias_length ||= query('SHOW max_identifier_length')[0][0].to_i
end
# QUOTING ==================================================
# Escapes binary strings for bytea input to the database.
def escape_bytea(value)
@connection.escape_bytea(value) if value
end
# 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.
def unescape_bytea(value)
@connection.unescape_bytea(value) if value
end
# Quotes PostgreSQL-specific data types for SQL input.
def quote(value, column = nil) #:nodoc:
return super unless column
case value
when Numeric
return super unless column.sql_type == 'money'
# Not truly string input, so doesn't require (or allow) escape string syntax.
"'#{value}'"
when String
case column.sql_type
when 'bytea' then "'#{escape_bytea(value)}'"
when 'xml' then "xml '#{quote_string(value)}'"
when /^bit/
case value
when /^[01]*$/ then "B'#{value}'" # Bit-string notation
when /^[0-9A-F]*$/i then "X'#{value}'" # Hexadecimal notation
end
else
super
end
else
super
end
end
# Quotes strings for use in SQL input.
def quote_string(s) #:nodoc:
@connection.escape(s)
end
# Checks the following cases:
#
# - table_name
# - "table.name"
# - schema_name.table_name
# - schema_name."table.name"
# - "schema.name".table_name
# - "schema.name"."table.name"
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
# Quotes column names for use in SQL queries.
def quote_column_name(name) #:nodoc:
PGconn.quote_ident(name.to_s)
end
# Quote date/time values for use in SQL input. Includes microseconds
# if the value is a Time responding to usec.
def quoted_date(value) #:nodoc:
if value.acts_like?(:time) && value.respond_to?(:usec)
"#{super}.#{sprintf("%06d", value.usec)}"
else
super
end
end
# Set the authorized user for this session
def session_auth=(user)
clear_cache!
exec_query "SET SESSION AUTHORIZATION #{user}"
end
# REFERENTIAL INTEGRITY ====================================
def supports_disable_referential_integrity?() #:nodoc:
true
end
def disable_referential_integrity #:nodoc:
if supports_disable_referential_integrity?() then
execute(tables.collect { |name| "ALTER TABLE #{quote_table_name(name)} DISABLE TRIGGER ALL" }.join(";"))
end
yield
ensure
if supports_disable_referential_integrity?() then
execute(tables.collect { |name| "ALTER TABLE #{quote_table_name(name)} ENABLE TRIGGER ALL" }.join(";"))
end
end
# DATABASE STATEMENTS ======================================
# Executes a SELECT query and returns an array of rows. Each row is an
# array of field values.
def select_rows(sql, name = nil)
select_raw(sql, name).last
end
# Executes an INSERT query and returns the new record's ID
def insert_sql(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
# Extract the table from the insert sql. Yuck.
table = sql.split(" ", 4)[2].gsub('"', '')
# If neither pk nor sequence name is given, look them up.
unless pk || sequence_name
pk, sequence_name = *pk_and_sequence_for(table)
end
if pk
select_value("#{sql} RETURNING #{quote_column_name(pk)}")
else
super
end
end
alias :create :insert
# create a 2D array representing the result set
def result_as_array(res) #:nodoc:
# check if we have any binary column and if they need escaping
unescape_col = []
res.nfields.times do |j|
unescape_col << res.ftype(j)
end
ary = []
res.ntuples.times do |i|
ary << []
res.nfields.times do |j|
data = res.getvalue(i,j)
case unescape_col[j]
# unescape string passed BYTEA field (OID == 17)
when BYTEA_COLUMN_TYPE_OID
data = unescape_bytea(data) if String === data
# If this is a money type column and there are any currency symbols,
# then strip them off. Indeed it would be prettier to do this in
# PostgreSQLColumn.string_to_decimal but would break form input
# fields that call value_before_type_cast.
when MONEY_COLUMN_TYPE_OID
# Because money output is formatted according to the locale, there are two
# cases to consider (note the decimal separators):
# (1) $12,345,678.12
# (2) $12.345.678,12
case data
when /^-?\D+[\d,]+\.\d{2}$/ # (1)
data.gsub!(/[^-\d.]/, '')
when /^-?\D+[\d.]+,\d{2}$/ # (2)
data.gsub!(/[^-\d,]/, '').sub!(/,/, '.')
end
end
ary[i] << data
end
end
return ary
end
# Queries the database and returns the results in an Array-like object
def query(sql, name = nil) #:nodoc:
log(sql, name) do
if @async
res = @connection.async_exec(sql)
else
res = @connection.exec(sql)
end
return result_as_array(res)
end
end
# Executes an SQL statement, returning a PGresult object on success
# or raising a PGError exception otherwise.
def execute(sql, name = nil)
log(sql, name) do
if @async
@connection.async_exec(sql)
else
@connection.exec(sql)
end
end
end
def substitute_for(column, current_values)
Arel.sql("$#{current_values.length + 1}")
end
def exec_query(sql, name = 'SQL', binds = [])
return exec_no_cache(sql, name) if binds.empty?
log(sql, name, binds) do
unless @statements.key? sql
nextkey = "a#{@statements.length + 1}"
@connection.prepare nextkey, sql
@statements[sql] = nextkey
end
key = @statements[sql]
# Clear the queue
@connection.get_last_result
@connection.send_query_prepared(key, binds.map { |col, val|
col ? col.type_cast(val) : val
})
@connection.block
result = @connection.get_last_result
ret = ActiveRecord::Result.new(result.fields, result_as_array(result))
result.clear
return ret
end
end
def exec_insert(sql, name, binds)
exec_query(sql, name, binds)
end
# Executes an UPDATE query and returns the number of affected tuples.
def update_sql(sql, name = nil)
super.cmd_tuples
end
# Begins a transaction.
def begin_db_transaction
execute "BEGIN"
end
# Commits a transaction.
def commit_db_transaction
execute "COMMIT"
end
# Aborts a transaction.
def rollback_db_transaction
execute "ROLLBACK"
end
def outside_transaction?
@connection.transaction_status == PGconn::PQTRANS_IDLE
end
def create_savepoint
execute("SAVEPOINT #{current_savepoint_name}")
end
def rollback_to_savepoint
execute("ROLLBACK TO SAVEPOINT #{current_savepoint_name}")
end
def release_savepoint
execute("RELEASE SAVEPOINT #{current_savepoint_name}")
end
# SCHEMA STATEMENTS ========================================
def recreate_database(name) #:nodoc:
drop_database(name)
create_database(name)
end
# 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'
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
# Drops a PostgreSQL database
#
# Example:
# drop_database 'matt_development'
def drop_database(name) #:nodoc:
execute "DROP DATABASE IF EXISTS #{quote_table_name(name)}"
end
# Returns the list of all tables in the schema search path or a specified schema.
def tables(name = nil)
query(<<-SQL, 'SCHEMA').map { |row| row[0] }
SELECT tablename
FROM pg_tables
WHERE schemaname = ANY (current_schemas(false))
SQL
end
def table_exists?(name)
name = name.to_s
schema, table = name.split('.', 2)
unless table # A table was provided without a schema
table = schema
schema = nil
end
if name =~ /^"/ # Handle quoted table names
table = name
schema = nil
end
query(<<-SQL, 'SCHEMA').first[0].to_i > 0
SELECT COUNT(*)
FROM pg_tables
WHERE tablename = '#{table.gsub(/(^"|"$)/,'')}'
#{schema ? "AND schemaname = '#{schema}'" : ''}
SQL
end
# Returns the list of all indexes for a table.
def indexes(table_name, name = nil)
schemas = schema_search_path.split(/,/).map { |p| quote(p) }.join(',')
result = query(<<-SQL, name)
SELECT distinct i.relname, d.indisunique, d.indkey, t.oid
FROM pg_class t, pg_class i, pg_index d
WHERE i.relkind = 'i'
AND d.indexrelid = i.oid
AND d.indisprimary = 'f'
AND t.oid = d.indrelid
AND t.relname = '#{table_name}'
AND i.relnamespace IN (SELECT oid FROM pg_namespace WHERE nspname IN (#{schemas}) )
ORDER BY i.relname
SQL
result.map do |row|
index_name = row[0]
unique = row[1] == 't'
indkey = row[2].split(" ")
oid = row[3]
columns = Hash[query(<<-SQL, "Columns for index #{row[0]} on #{table_name}")]
SELECT a.attnum, a.attname
FROM pg_attribute a
WHERE a.attrelid = #{oid}
AND a.attnum IN (#{indkey.join(",")})
SQL
column_names = columns.values_at(*indkey).compact
column_names.empty? ? nil : IndexDefinition.new(table_name, index_name, unique, column_names)
end.compact
end
# Returns the list of all column definitions for a table.
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
# Returns the current database name.
def current_database
query('select current_database()')[0][0]
end
# Returns the current database encoding format.
def encoding
query(<<-end_sql)[0][0]
SELECT pg_encoding_to_char(pg_database.encoding) FROM pg_database
WHERE pg_database.datname LIKE '#{current_database}'
end_sql
end
# 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: http://www.postgresql.org/docs/current/static/ddl-schemas.html
#
# This should be not be called manually but set in database.yml.
def schema_search_path=(schema_csv)
if schema_csv
execute "SET search_path TO #{schema_csv}"
@schema_search_path = schema_csv
end
end
# Returns the active schema search path.
def schema_search_path
@schema_search_path ||= query('SHOW search_path')[0][0]
end
# Returns the current client message level.
def client_min_messages
query('SHOW client_min_messages', 'SCHEMA')[0][0]
end
# Set the client message level.
def client_min_messages=(level)
execute("SET client_min_messages TO '#{level}'", 'SCHEMA')
end
# Returns the sequence name for a table's primary key or some other specified key.
def default_sequence_name(table_name, pk = nil) #:nodoc:
default_pk, default_seq = pk_and_sequence_for(table_name)
default_seq || "#{table_name}_#{pk || default_pk || 'id'}_seq"
end
# Resets the sequence of a table's primary key to the maximum value.
def reset_pk_sequence!(table, pk = nil, sequence = nil) #:nodoc:
unless pk and sequence
default_pk, default_sequence = pk_and_sequence_for(table)
pk ||= default_pk
sequence ||= default_sequence
end
if pk
if sequence
quoted_sequence = quote_column_name(sequence)
select_value <<-end_sql, 'Reset sequence'
SELECT setval('#{quoted_sequence}', (SELECT COALESCE(MAX(#{quote_column_name pk})+(SELECT increment_by FROM #{quoted_sequence}), (SELECT min_value FROM #{quoted_sequence})) FROM #{quote_table_name(table)}), false)
end_sql
else
@logger.warn "#{table} has primary key #{pk} with no default sequence" if @logger
end
end
end
# Returns a table's primary key and belonging sequence.
def pk_and_sequence_for(table) #:nodoc:
# First try looking for a sequence with a dependency on the
# given table's primary key.
result = exec_query(<<-end_sql, 'SCHEMA').rows.first
SELECT attr.attname, seq.relname
FROM pg_class seq,
pg_attribute attr,
pg_depend dep,
pg_namespace name,
pg_constraint cons
WHERE seq.oid = dep.objid
AND seq.relkind = 'S'
AND attr.attrelid = dep.refobjid
AND attr.attnum = dep.refobjsubid
AND attr.attrelid = cons.conrelid
AND attr.attnum = cons.conkey[1]
AND cons.contype = 'p'
AND dep.refobjid = '#{quote_table_name(table)}'::regclass
end_sql
# [primary_key, sequence]
[result.first, result.last]
rescue
nil
end
# Returns just a table's primary key
def primary_key(table)
row = exec_query(<<-end_sql, 'SCHEMA', [[nil, table]]).rows.first
SELECT DISTINCT(attr.attname)
FROM pg_attribute attr,
pg_depend dep,
pg_namespace name,
pg_constraint cons
WHERE attr.attrelid = dep.refobjid
AND attr.attnum = dep.refobjsubid
AND attr.attrelid = cons.conrelid
AND attr.attnum = cons.conkey[1]
AND cons.contype = 'p'
AND dep.refobjid = $1::regclass
end_sql
row && row.first
end
# Renames a table.
def rename_table(name, new_name)
execute "ALTER TABLE #{quote_table_name(name)} RENAME TO #{quote_table_name(new_name)}"
end
# Adds a new column to the named table.
# See TableDefinition#column for details of the options you can use.
def add_column(table_name, column_name, type, options = {})
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
# Changes the column of a table.
def change_column(table_name, column_name, type, options = {})
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
# Changes the default value of a table column.
def change_column_default(table_name, column_name, default)
execute "ALTER TABLE #{quote_table_name(table_name)} ALTER COLUMN #{quote_column_name(column_name)} SET DEFAULT #{quote(default)}"
end
def change_column_null(table_name, column_name, null, default = nil)
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
# Renames a column in a table.
def rename_column(table_name, column_name, new_column_name)
execute "ALTER TABLE #{quote_table_name(table_name)} RENAME COLUMN #{quote_column_name(column_name)} TO #{quote_column_name(new_column_name)}"
end
def remove_index!(table_name, index_name) #:nodoc:
execute "DROP INDEX #{quote_table_name(index_name)}"
end
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
def index_name_length
63
end
# Maps logical Rails types to PostgreSQL-specific data types.
def type_to_sql(type, limit = nil, precision = nil, scale = nil)
return super unless type.to_s == '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
end
# Returns a SELECT DISTINCT clause for a given set of columns and a given ORDER BY clause.
#
# PostgreSQL requires the ORDER BY columns in the select list for distinct queries, and
# requires that the ORDER BY include the distinct column.
#
# distinct("posts.id", "posts.created_at desc")
def distinct(columns, orders) #:nodoc:
return "DISTINCT #{columns}" if orders.empty?
# Construct a clean list of column names from the ORDER BY clause, removing
# any ASC/DESC modifiers
order_columns = orders.collect { |s| s =~ /^(.+)\s+(ASC|DESC)\s*$/i ? $1 : s }
order_columns.delete_if { |c| c.blank? }
order_columns = order_columns.zip((0...order_columns.size).to_a).map { |s,i| "#{s} AS alias_#{i}" }
# Return a DISTINCT ON() clause that's distinct on the columns we want but includes
# all the required columns for the ORDER BY to work properly.
sql = "DISTINCT ON (#{columns}) #{columns}, "
sql << order_columns * ', '
end
protected
# Returns the version of the connected PostgreSQL version.
def postgresql_version
@postgresql_version ||=
if @connection.respond_to?(:server_version)
@connection.server_version
else
# Mimic PGconn.server_version behavior
begin
if query('SELECT version()')[0][0] =~ /PostgreSQL ([0-9.]+)/
major, minor, tiny = $1.split(".")
(major.to_i * 10000) + (minor.to_i * 100) + tiny.to_i
else
0
end
rescue
0
end
end
end
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
private
def exec_no_cache(sql, name)
log(sql, name) do
result = @connection.async_exec(sql)
ret = ActiveRecord::Result.new(result.fields, result_as_array(result))
result.clear
ret
end
end
# The internal PostgreSQL identifier of the money data type.
MONEY_COLUMN_TYPE_OID = 790 #:nodoc:
# The internal PostgreSQL identifier of the BYTEA data type.
BYTEA_COLUMN_TYPE_OID = 17 #:nodoc:
# Connects to a PostgreSQL server and sets up the adapter depending on the
# connected server's characteristics.
def connect
@connection = PGconn.connect(*@connection_parameters)
PGconn.translate_results = false if PGconn.respond_to?(:translate_results=)
# Ignore async_exec and async_query when using postgres-pr.
@async = @connection.respond_to?(:async_exec)
# 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.
PostgreSQLColumn.money_precision = (postgresql_version >= 80300) ? 19 : 10
configure_connection
end
# Configures the encoding, verbosity, schema search path, and time zone of the connection.
# This is called by #connect and should not be called manually.
def configure_connection
if @config[:encoding]
if @connection.respond_to?(:set_client_encoding)
@connection.set_client_encoding(@config[:encoding])
else
execute("SET client_encoding TO '#{@config[:encoding]}'")
end
end
self.client_min_messages = @config[:min_messages] if @config[:min_messages]
self.schema_search_path = @config[:schema_search_path] || @config[:schema_order]
# Use standard-conforming strings if available 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.
if ActiveRecord::Base.default_timezone == :utc
execute("SET time zone 'UTC'", 'SCHEMA')
elsif @local_tz
execute("SET time zone '#{@local_tz}'", 'SCHEMA')
end
end
# Returns the current ID of a table's sequence.
def last_insert_id(sequence_name) #:nodoc:
r = exec_query("SELECT currval($1)", 'SQL', [[nil, sequence_name]])
Integer(r.rows.first.first)
end
# Executes a SELECT query and returns the results, performing any data type
# conversions that are required to be performed here instead of in PostgreSQLColumn.
def select(sql, name = nil, binds = [])
exec_query(sql, name, binds).to_a
end
def select_raw(sql, name = nil)
res = execute(sql, name)
results = result_as_array(res)
fields = res.fields
res.clear
return fields, results
end
# Returns the list of a table's column names, data types, and default values.
#
# The underlying query is roughly:
# SELECT column.name, column.type, default.value
# FROM column LEFT JOIN default
# ON column.table_id = default.table_id
# AND column.num = default.column_num
# WHERE column.table_id = get_table_id('table_name')
# AND column.num > 0
# AND NOT column.is_dropped
# ORDER BY column.num
#
# If the table name is not prefixed with a schema, the database will
# take the first match from the schema search path.
#
# Query implementation notes:
# - format_type includes the column size constraint, e.g. varchar(50)
# - ::regclass is a function that gives the id for a table name
def column_definitions(table_name) #:nodoc:
exec_query(<<-end_sql, 'SCHEMA').rows
SELECT a.attname, format_type(a.atttypid, a.atttypmod), d.adsrc, a.attnotnull
FROM pg_attribute a LEFT JOIN pg_attrdef d
ON a.attrelid = d.adrelid AND a.attnum = d.adnum
WHERE a.attrelid = '#{quote_table_name(table_name)}'::regclass
AND a.attnum > 0 AND NOT a.attisdropped
ORDER BY a.attnum
end_sql
end
def extract_pg_identifier_from_name(name)
match_data = name.start_with?('"') ? name.match(/\"([^\"]+)\"/) : name.match(/([^\.]+)/)
if match_data
rest = name[match_data[0].length, name.length]
rest = rest[1, rest.length] if rest.start_with? "."
[match_data[1], (rest.length > 0 ? rest : nil)]
end
end
def table_definition
TableDefinition.new(self)
end
end
end
end