Class: ActiveRecord::ConnectionAdapters::PostgreSQLAdapter

Inherits:
AbstractAdapter
  • Object
show all
Defined in:
lib/active_record/connection_adapters/postgresql_adapter.rb

Overview

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:

  • :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 <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.

Defined Under Namespace

Modules: Utils Classes: BindSubstitution, ExplainPrettyPrinter, StatementPool, TableDefinition

Constant Summary collapse

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" },
  :tsvector    => { :name => "tsvector" }
}

Instance Attribute Summary

Attributes inherited from AbstractAdapter

#in_use, #last_use, #logger, #open_transactions, #pool, #schema_cache, #visitor

Attributes included from QueryCache

#query_cache, #query_cache_enabled

Instance Method Summary collapse

Methods inherited from AbstractAdapter

#case_insensitive_comparison, #case_sensitive_modifier, #close, #current_savepoint_name, #decrement_open_transactions, #expire, #increment_open_transactions, #lease, #prefetch_primary_key?, #raw_connection, #requires_reloading?, #supports_bulk_alter?, #supports_count_distinct?, #transaction_joinable=, #verify!

Methods included from QueryCache

#cache, #clear_query_cache, dirties_query_cache, #disable_query_cache!, #enable_query_cache!, included, #select_all, #uncached

Methods included from DatabaseLimits

#column_name_length, #columns_per_multicolumn_index, #columns_per_table, #in_clause_length, #indexes_per_table, #joins_per_query, #sql_query_length, #table_name_length

Methods included from Quoting

#quoted_false, #quoted_true

Methods included from DatabaseStatements

#add_transaction_record, #case_sensitive_equality_operator, #delete, #empty_insert_statement_value, #exec_insert, #insert, #insert_fixture, #join_to_update, #limited_update_conditions, #reset_sequence!, #sanitize_limit, #select_all, #select_one, #select_value, #select_values, #to_sql, #transaction, #update

Methods included from SchemaStatements

#add_column_options!, #add_index, #add_timestamps, #assume_migrated_upto_version, #change_table, #column_exists?, #create_table, #drop_table, #dump_schema_information, #index_exists?, #index_name, #index_name_exists?, #initialize_schema_migrations_table, #remove_column, #remove_index, #remove_timestamps, #structure_dump, #table_alias_for

Constructor Details

#initialize(connection, logger, connection_parameters, config) ⇒ PostgreSQLAdapter

Initializes and connects a PostgreSQL adapter.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 309

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, @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

Instance Method Details

#active? ⇒ Boolean

Is this connection alive and ready for queries?

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 341

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

#adapter_name ⇒ Object

Returns ‘PostgreSQL’ as adapter name for identification purposes.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 238

def adapter_name
  ADAPTER_NAME
end

#add_column(table_name, column_name, type, options = {}) ⇒ Object

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



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 1017

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 ⇒ Object

Begins a transaction.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 698

def begin_db_transaction
  execute "BEGIN"
end

#change_column(table_name, column_name, type, options = {}) ⇒ Object

Changes the column of a table.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 1026

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) ⇒ Object

Changes the default value of a table column.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 1037

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) ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 1042

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! ⇒ Object

Clears the prepared statements cache.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 336

def clear_cache!
  @statements.clear
end

#client_min_messages ⇒ Object

Returns the current client message level.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 896

def client_min_messages
  query('SHOW client_min_messages', 'SCHEMA')[0][0]
end

#client_min_messages=(level) ⇒ Object

Set the client message level.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 901

def client_min_messages=(level)
  execute("SET client_min_messages TO '#{level}'", 'SCHEMA')
end

#columns(table_name, name = nil) ⇒ Object

Returns the list of all column definitions for a table.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 853

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 ⇒ Object

Commits a transaction.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 703

def commit_db_transaction
  execute "COMMIT"
end

#create_database(name, options = {}) ⇒ Object

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'



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 744

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 ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 716

def create_savepoint
  execute("SAVEPOINT #{current_savepoint_name}")
end

#current_database ⇒ Object

Returns the current database name.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 861

def current_database
  query('select current_database()', 'SCHEMA')[0][0]
end

#current_schema ⇒ Object

Returns the current schema name.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 866

def current_schema
  query('SELECT current_schema', 'SCHEMA')[0][0]
end

#default_sequence_name(table_name, pk = nil) ⇒ Object

Returns the sequence name for a table’s primary key or some other specified key.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 906

def default_sequence_name(table_name, pk = nil) #:nodoc:
  serial_sequence(table_name, pk || 'id').split('.').last
rescue ActiveRecord::StatementInvalid
  "#{table_name}_#{pk || 'id'}_seq"
end

#disable_referential_integrity ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 519

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

#disconnect! ⇒ Object

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



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 363

def disconnect!
  clear_cache!
  @connection.close rescue nil
end

#distinct(columns, orders) ⇒ Object

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")



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 1105

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.gsub(/\s+(ASC|DESC)\s*(NULLS\s+(FIRST|LAST)\s*)?/i, '') }
  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}" }

  "DISTINCT #{columns}, #{order_columns * ', '}"
end

#drop_database(name) ⇒ Object

Drops a PostgreSQL database.

Example:

drop_database 'matt_development'



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 771

def drop_database(name) #:nodoc:
  execute "DROP DATABASE IF EXISTS #{quote_table_name(name)}"
end

#encoding ⇒ Object

Returns the current database encoding format.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 871

def encoding
  query(<<-end_sql, 'SCHEMA')[0][0]
    SELECT pg_encoding_to_char(pg_database.encoding) FROM pg_database
    WHERE pg_database.datname LIKE '#{current_database}'
  end_sql
end

#escape_bytea(value) ⇒ Object

Escapes binary strings for bytea input to the database.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 416

def escape_bytea(value)
  @connection.escape_bytea(value) if value
end

#exec_delete(sql, name = 'SQL', binds = []) ⇒ Object Also known as: exec_update 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 669

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

#exec_query(sql, name = 'SQL', binds = []) ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 658

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

#execute(sql, name = nil) ⇒ Object

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



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 648

def execute(sql, name = nil)
  log(sql, name) do
    @connection.async_exec(sql)
  end
end

#explain(arel, binds = []) ⇒ Object

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



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 532

def explain(arel, binds = [])
  sql = "EXPLAIN #{to_sql(arel, binds)}"
  ExplainPrettyPrinter.new.pp(exec_query(sql, 'EXPLAIN', binds))
end

#index_name_length ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 1064

def index_name_length
  63
end

#indexes(table_name, name = nil) ⇒ Object

Returns an array of indexes for the given table.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 814

def indexes(table_name, name = nil)
   result = query(<<-SQL, 'SCHEMA')
     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
  SQL


  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(<<-SQL, "SCHEMA")]
    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

    # 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) ⇒ Object

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



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 581

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

#native_database_types ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 368

def native_database_types #:nodoc:
  NATIVE_DATABASE_TYPES
end

#outside_transaction? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 712

def outside_transaction?
  @connection.transaction_status == PGconn::PQTRANS_IDLE
end

#pk_and_sequence_for(table) ⇒ Object

Returns a table’s primary key and belonging sequence.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 942

def pk_and_sequence_for(table) #:nodoc:
  # First try looking for a sequence with a dependency on the
  # given table's primary key.
  result = query(<<-end_sql, 'SCHEMA')[0]
    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

  if result.nil? or result.empty?
    result = query(<<-end_sql, 'SCHEMA')[0]
      SELECT attr.attname,
        CASE
          WHEN split_part(pg_get_expr(def.adbin, def.adrelid), '''', 2) ~ '.' THEN
            substr(split_part(pg_get_expr(def.adbin, def.adrelid), '''', 2),
                   strpos(split_part(pg_get_expr(def.adbin, def.adrelid), '''', 2), '.')+1)
          ELSE split_part(pg_get_expr(def.adbin, def.adrelid), '''', 2)
        END
      FROM pg_class       t
      JOIN pg_attribute   attr ON (t.oid = attrelid)
      JOIN pg_attrdef     def  ON (adrelid = attrelid AND adnum = attnum)
      JOIN pg_constraint  cons ON (conrelid = adrelid AND adnum = conkey[1])
      WHERE t.oid = '#{quote_table_name(table)}'::regclass
        AND cons.contype = 'p'
        AND pg_get_expr(def.adbin, def.adrelid) ~* 'nextval'
    end_sql
  end

  [result.first, result.last]
rescue
  nil
end

#primary_key(table) ⇒ Object

Returns just a table’s primary key



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 987

def primary_key(table)
  row = exec_query(<<-end_sql, 'SCHEMA').rows.first
    SELECT attr.attname
    FROM pg_attribute attr
    INNER JOIN pg_constraint cons ON attr.attrelid = cons.conrelid AND attr.attnum = cons.conkey[1]
    WHERE cons.contype = 'p'
      AND cons.conrelid = '#{quote_table_name(table)}'::regclass
  end_sql

  row && row.first
end

#query(sql, name = nil) ⇒ Object

Queries the database and returns the results in an Array-like object



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 640

def query(sql, name = nil) #:nodoc:
  log(sql, name) do
    result_as_array @connection.async_exec(sql)
  end
end

#quote(value, column = nil) ⇒ Object

Quotes PostgreSQL-specific data types for SQL input.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 428

def quote(value, column = nil) #:nodoc:
  return super unless column

  case value
  when Float
    return super unless value.infinite? && column.type == :datetime
    "'#{value.to_s.downcase}'"
  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 /\A[01]*\Z/      then "B'#{value}'" # Bit-string notation
      when /\A[0-9A-F]*\Z/i then "X'#{value}'" # Hexadecimal notation
      end
    else
      super
    end
  else
    super
  end
end

#quote_column_name(name) ⇒ Object

Quotes column names for use in SQL queries.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 493

def quote_column_name(name) #:nodoc:
  PGconn.quote_ident(name.to_s)
end

#quote_string(s) ⇒ Object

Quotes strings for use in SQL input.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 469

def quote_string(s) #:nodoc:
  @connection.escape(s)
end

#quote_table_name(name) ⇒ Object

Checks the following cases:

  • table_name

  • “table.name”

  • schema_name.table_name

  • schema_name.“table.name”

  • “schema.name”.table_name

  • “schema.name”.“table.name”



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 481

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

#quoted_date(value) ⇒ Object

Quote date/time values for use in SQL input. Includes microseconds if the value is a Time responding to usec.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 499

def quoted_date(value) #:nodoc:
  if value.acts_like?(:time) && value.respond_to?(:usec)
    "#{super}.#{sprintf("%06d", value.usec)}"
  else
    super
  end
end

#reconnect! ⇒ Object

Close then reopen the connection.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 349

def reconnect!
  clear_cache!
  @connection.reset
  @open_transactions = 0
  configure_connection
end

#recreate_database(name, options = {}) ⇒ Object

Drops the database specified on the name attribute and creates it again using the provided options.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 732

def recreate_database(name, options = {}) #:nodoc:
  drop_database(name)
  create_database(name, options)
end

#release_savepoint ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 724

def release_savepoint
  execute("RELEASE SAVEPOINT #{current_savepoint_name}")
end

#remove_index!(table_name, index_name) ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 1056

def remove_index!(table_name, index_name) #:nodoc:
  execute "DROP INDEX #{quote_table_name(index_name)}"
end

#rename_column(table_name, column_name, new_column_name) ⇒ Object

Renames a column in a table.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 1051

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) ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 1060

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) ⇒ Object

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')



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 1005

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! ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 356

def reset!
  clear_cache!
  super
end

#reset_pk_sequence!(table, pk = nil, sequence = nil) ⇒ Object

Resets the sequence of a table’s primary key to the maximum value.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 920

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 @logger && pk && !sequence
    @logger.warn "#{table} has primary key #{pk} with no default sequence"
  end

  if pk && sequence
    quoted_sequence = quote_table_name(sequence)

    select_value <<-end_sql, 'SCHEMA'
      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
  end
end

#result_as_array(res) ⇒ Object

create a 2D array representing the result set



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 597

def result_as_array(res) #:nodoc:
  # check if we have any binary column and if they need escaping
  ftypes = Array.new(res.nfields) do |i|
    [i, res.ftype(i)]
  end

  rows = res.values
  return rows unless ftypes.any? { |_, x|
    x == BYTEA_COLUMN_TYPE_OID || x == MONEY_COLUMN_TYPE_OID
  }

  typehash = ftypes.group_by { |_, type| type }
  binaries = typehash[BYTEA_COLUMN_TYPE_OID] || []
  monies   = typehash[MONEY_COLUMN_TYPE_OID] || []

  rows.each do |row|
    # unescape string passed BYTEA field (OID == 17)
    binaries.each do |index, _|
      row[index] = unescape_bytea(row[index])
    end

    # 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.
    monies.each do |index, _|
      data = row[index]
      # 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
  end
end

#rollback_db_transaction ⇒ Object

Aborts a transaction.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 708

def rollback_db_transaction
  execute "ROLLBACK"
end

#rollback_to_savepoint ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 720

def rollback_to_savepoint
  execute("ROLLBACK TO SAVEPOINT #{current_savepoint_name}")
end

#schema_exists?(name) ⇒ Boolean

Returns true if schema exists.

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 805

def schema_exists?(name)
  exec_query(<<-SQL, 'SCHEMA').rows.first[0].to_i > 0
    SELECT COUNT(*)
    FROM pg_namespace
    WHERE nspname = '#{name}'
  SQL
end

#schema_search_path ⇒ Object

Returns the active schema search path.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 891

def schema_search_path
  @schema_search_path ||= query('SHOW search_path', 'SCHEMA')[0][0]
end

#schema_search_path=(schema_csv) ⇒ Object

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.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 883

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) ⇒ Object

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



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 576

def select_rows(sql, name = nil)
  select_raw(sql, name).last
end

#serial_sequence(table, column) ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 912

def serial_sequence(table, column)
  result = exec_query(<<-eosql, 'SCHEMA')
    SELECT pg_get_serial_sequence('#{table}', '#{column}')
  eosql
  result.rows.first.first
end

#session_auth=(user) ⇒ Object

Set the authorized user for this session



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 508

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

#set_standard_conforming_strings ⇒ Object

Enable standard-conforming strings if available.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 383

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) ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 680

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) ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 654

def substitute_at(column, index)
  Arel::Nodes::BindParam.new "$#{index + 1}"
end

#supports_ddl_transactions? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 394

def supports_ddl_transactions?
  true
end

#supports_disable_referential_integrity? ⇒ Boolean

REFERENTIAL INTEGRITY ====================================

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 515

def supports_disable_referential_integrity? #:nodoc:
  true
end

#supports_explain? ⇒ Boolean

Returns true.

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 404

def supports_explain?
  true
end

#supports_index_sort_order? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 248

def supports_index_sort_order?
  true
end

#supports_insert_with_returning? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 390

def supports_insert_with_returning?
  true
end

#supports_migrations? ⇒ Boolean

Returns true, since this connection adapter supports migrations.

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 373

def supports_migrations?
  true
end

#supports_primary_key? ⇒ Boolean

Does PostgreSQL support finding primary key on non-Active Record tables?

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 378

def supports_primary_key? #:nodoc:
  true
end

#supports_savepoints? ⇒ Boolean

Returns true, since this connection adapter supports savepoints.

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 399

def supports_savepoints?
  true
end

#supports_statement_cache? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 244

def supports_statement_cache?
  true
end

#table_alias_length ⇒ Object

Returns the configured supported identifier length supported by PostgreSQL



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 409

def table_alias_length
  @table_alias_length ||= query('SHOW max_identifier_length')[0][0].to_i
end

#table_exists?(name) ⇒ Boolean

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)

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 787

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(<<-SQL, 'SCHEMA').rows.first[0].to_i > 0
      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 = '#{table.gsub(/(^"|"$)/,'')}'
      AND n.nspname = #{schema ? "'#{schema}'" : 'ANY (current_schemas(false))'}
  SQL
end

#tables(name = nil) ⇒ Object

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



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 776

def tables(name = nil)
  query(<<-SQL, 'SCHEMA').map { |row| row[0] }
    SELECT tablename
    FROM pg_tables
    WHERE schemaname = ANY (current_schemas(false))
  SQL
end

#type_cast(value, column) ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 456

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) ⇒ Object

Maps logical Rails types to PostgreSQL-specific data types.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 1069

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 'text'
    # PostgreSQL doesn't support limits on text columns.
    # The hard limit is 1Gb, according to section 8.3 in the manual.
    case limit
    when nil, 0..0x3fffffff; super(type)
    else raise(ActiveRecordError, "The limit on text can be at most 1GB - 1byte.")
    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) ⇒ Object

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.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 423

def unescape_bytea(value)
  @connection.unescape_bytea(value) if value
end

#update_sql(sql, name = nil) ⇒ Object

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



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 693

def update_sql(sql, name = nil)
  super.cmd_tuples
end