Modularize postgresql adapter

1 files changed, 136 insertions, 985 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index 40cd65cce9..956e83bfd8 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -1,6 +1,11 @@
 require 'active_record/connection_adapters/abstract_adapter'
 require 'active_record/connection_adapters/statement_pool'
 require 'active_record/connection_adapters/postgresql/oid'
+require 'active_record/connection_adapters/postgresql/cast'
+require 'active_record/connection_adapters/postgresql/quoting'
+require 'active_record/connection_adapters/postgresql/schema_statements'
+require 'active_record/connection_adapters/postgresql/database_statements'
+require 'active_record/connection_adapters/postgresql/referential_integrity'
 require 'arel/visitors/bind_visitor'
 
 # Make sure we're using pg high enough for PGResult#values
@@ -44,72 +49,9 @@ module ActiveRecord
 
       # :stopdoc:
       class << self
-        attr_accessor :money_precision
-        def string_to_time(string)
-          return string unless String === string
-
-          case string
-          when 'infinity'  then 1.0 / 0.0
-          when '-infinity' then -1.0 / 0.0
-          else
-            super
-          end
-        end
-
-        def hstore_to_string(object)
-          if Hash === object
-            object.map { |k,v|
-              "#{escape_hstore(k)}=>#{escape_hstore(v)}"
-            }.join ','
-          else
-            object
-          end
-        end
-
-        def string_to_hstore(string)
-          if string.nil?
-            nil
-          elsif String === string
-            Hash[string.scan(HstorePair).map { |k,v|
-              v = v.upcase == 'NULL' ? nil : v.gsub(/^"(.*)"$/,'\1').gsub(/\\(.)/, '\1')
-              k = k.gsub(/^"(.*)"$/,'\1').gsub(/\\(.)/, '\1')
-              [k,v]
-            }]
-          else
-            string
-          end
-        end
-
-        def string_to_cidr(string)
-          if string.nil?
-            nil
-          elsif String === string
-            IPAddr.new(string)
-          else
-            string
-          end
-        end
+        include ConnectionAdapters::PostgreSQLColumn::Cast
 
-        def cidr_to_string(object)
-          if IPAddr === object
-            "#{object.to_s}/#{object.instance_variable_get(:@mask_addr).to_s(2).count('1')}"
-          else
-            object
-          end
-        end
-
-        private
-        HstorePair = begin
-          quoted_string = /"[^"\\]*(?:\\.[^"\\]*)*"/
-          unquoted_string = /(?:\\.|[^\s,])[^\s=,\\]*(?:\\.[^\s=,\\]*|=[^,>])*/
-          /(#{quoted_string}|#{unquoted_string})\s*=>\s*(#{quoted_string}|#{unquoted_string})/
-        end
-
-        def escape_hstore(value)
-            value.nil?         ? 'NULL'
-          : value == ""        ? '""'
-          :                      '"%s"' % value.to_s.gsub(/(["\\])/, '\\\\\1')
-        end
+        attr_accessor :money_precision
       end
       # :startdoc:
 
@@ -182,90 +124,91 @@ module ActiveRecord
       end
 
       private
-      def extract_limit(sql_type)
-        case sql_type
-        when /^bigint/i;    8
-        when /^smallint/i;  2
-        when /^timestamp/i; nil
-        else super
+
+        def extract_limit(sql_type)
+          case sql_type
+          when /^bigint/i;    8
+          when /^smallint/i;  2
+          when /^timestamp/i; nil
+          else super
+          end
         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 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
-        elsif sql_type =~ /timestamp/i
-          $1.to_i if sql_type =~ /\((\d+)\)/
-        else
-          super
+        # Extracts the precision from PostgreSQL-specific data types.
+        def extract_precision(sql_type)
+          if sql_type == 'money'
+            self.class.money_precision
+          elsif sql_type =~ /timestamp/i
+            $1.to_i if sql_type =~ /\((\d+)\)/
+          else
+            super
+          end
         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
-        when 'hstore'
-          :hstore
-        # Network address types
-        when 'inet'
-          :inet
-        when 'cidr'
-          :cidr
-        when 'macaddr'
-          :macaddr
-        # 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
-        # Bit strings
-        when /^bit(?: varying)?(?:\(\d+\))?$/
-          :string
-        # XML type
-        when 'xml'
-          :xml
-        # tsvector type
-        when 'tsvector'
-          :tsvector
-        # Arrays
-        when /^\D+\[\]$/
-          :string
-        # Object identifier types
-        when 'oid'
-          :integer
-        # UUID type
-        when 'uuid'
-          :uuid
-        # Small and big integer types
-        when /^(?:small|big)int$/
-          :integer
-        # Pass through all types that are not specific to PostgreSQL.
-        else
-          super
+        # 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
+          when 'hstore'
+            :hstore
+          # Network address types
+          when 'inet'
+            :inet
+          when 'cidr'
+            :cidr
+          when 'macaddr'
+            :macaddr
+          # 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
+          # Bit strings
+          when /^bit(?: varying)?(?:\(\d+\))?$/
+            :string
+          # XML type
+          when 'xml'
+            :xml
+          # tsvector type
+          when 'tsvector'
+            :tsvector
+          # Arrays
+          when /^\D+\[\]$/
+            :string
+          # Object identifier types
+          when 'oid'
+            :integer
+          # UUID type
+          when 'uuid'
+            :uuid
+          # Small and big integer types
+          when /^(?:small|big)int$/
+            :integer
+          # Pass through all types that are not specific to PostgreSQL.
+          else
+            super
+          end
         end
-      end
     end
 
     # The PostgreSQL adapter works with the native C (https://bitbucket.org/ged/ruby-pg) driver.
@@ -329,27 +272,32 @@ module ActiveRecord
       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" },
-        :hstore      => { :name => "hstore" },
-        :inet        => { :name => "inet" },
-        :cidr        => { :name => "cidr" },
-        :macaddr     => { :name => "macaddr" },
-        :uuid        => { :name => "uuid" }
+        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" },
+        hstore:      { name: "hstore" },
+        inet:        { name: "inet" },
+        cidr:        { name: "cidr" },
+        macaddr:     { name: "macaddr" },
+        uuid:        { name: "uuid" }
       }
 
+      include Quoting
+      include ReferentialIntegrity
+      include SchemaStatements
+      include DatabaseStatements
+
       # Returns 'PostgreSQL' as adapter name for identification purposes.
       def adapter_name
         ADAPTER_NAME
@@ -406,19 +354,20 @@ module ActiveRecord
         end
 
         private
-        def cache
-          @cache[Process.pid]
-        end
 
-        def dealloc(key)
-          @connection.query "DEALLOCATE #{key}" if connection_active?
-        end
+          def cache
+            @cache[Process.pid]
+          end
 
-        def connection_active?
-          @connection.status == PGconn::CONNECTION_OK
-        rescue PGError
-          false
-        end
+          def dealloc(key)
+            @connection.query "DEALLOCATE #{key}" if connection_active?
+          end
+
+          def connection_active?
+            @connection.status == PGconn::CONNECTION_OK
+          rescue PGError
+            false
+          end
       end
 
       class BindSubstitution < Arel::Visitors::PostgreSQL # :nodoc:
@@ -534,812 +483,12 @@ module ActiveRecord
         @table_alias_length ||= query('SHOW max_identifier_length', 'SCHEMA')[0][0].to_i
       end
 
-      # QUOTING ==================================================
-
-      # Escapes binary strings for bytea input to the database.
-      def escape_bytea(value)
-        PGconn.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)
-        PGconn.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 Hash
-          case column.sql_type
-          when 'hstore' then super(PostgreSQLColumn.hstore_to_string(value), column)
-          else super
-          end
-        when IPAddr
-          case column.sql_type
-          when 'inet', 'cidr' then super(PostgreSQLColumn.cidr_to_string(value), column)
-          else super
-          end
-        when Float
-          if value.infinite? && column.type == :datetime
-            "'#{value.to_s.downcase}'"
-          elsif value.infinite? || value.nan?
-            "'#{value.to_s}'"
-          else
-            super
-          end
-        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
-
-      def type_cast(value, column)
-        return super unless column
-
-        case value
-        when String
-          return super unless 'bytea' == column.sql_type
-          { :value => value, :format => 1 }
-        when Hash
-          return super unless 'hstore' == column.sql_type
-          PostgreSQLColumn.hstore_to_string(value)
-        when IPAddr
-          return super unless ['inet','cidr'].includes? column.sql_type
-          PostgreSQLColumn.cidr_to_string(value)
-        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 ======================================
-
-      def explain(arel, binds = [])
-        sql = "EXPLAIN #{to_sql(arel, binds)}"
-        ExplainPrettyPrinter.new.pp(exec_query(sql, 'EXPLAIN', binds))
-      end
-
-      class ExplainPrettyPrinter # :nodoc:
-        # Pretty prints the result of a EXPLAIN in a way that resembles the output of the
-        # PostgreSQL shell:
-        #
-        #                                     QUERY PLAN
-        #   ------------------------------------------------------------------------------
-        #    Nested Loop Left Join  (cost=0.00..37.24 rows=8 width=0)
-        #      Join Filter: (posts.user_id = users.id)
-        #      ->  Index Scan using users_pkey on users  (cost=0.00..8.27 rows=1 width=4)
-        #            Index Cond: (id = 1)
-        #      ->  Seq Scan on posts  (cost=0.00..28.88 rows=8 width=4)
-        #            Filter: (posts.user_id = 1)
-        #   (6 rows)
-        #
-        def pp(result)
-          header = result.columns.first
-          lines  = result.rows.map(&:first)
-
-          # We add 2 because there's one char of padding at both sides, note
-          # the extra hyphens in the example above.
-          width = [header, *lines].map(&:length).max + 2
-
-          pp = []
-
-          pp << header.center(width).rstrip
-          pp << '-' * width
-
-          pp += lines.map {|line| " #{line}"}
-
-          nrows = result.rows.length
-          rows_label = nrows == 1 ? 'row' : 'rows'
-          pp << "(#{nrows} #{rows_label})"
-
-          pp.join("\n") + "\n"
-        end
-      end
-
-      # 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)
-        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 && use_insert_returning?
-          select_value("#{sql} RETURNING #{quote_column_name(pk)}")
-        elsif pk
-          super
-          last_insert_id_value(sequence_name || default_sequence_name(table_ref, 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
-        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}$/  # (2)
-              data.gsub!(/[^-\d,]/, '').sub!(/,/, '.')
-            end
-          end
-        end
-      end
-
-
-      # Queries the database and returns the results in an Array-like object
-      def query(sql, name = nil) #:nodoc:
-        log(sql, name) do
-          result_as_array @connection.async_exec(sql)
-        end
-      end
-
-      # Executes an SQL statement, returning a PGresult object on success
-      # or raising a PGError exception otherwise.
-      def execute(sql, name = nil)
-        log(sql, name) do
-          @connection.async_exec(sql)
-        end
-      end
-
-      def substitute_at(column, index)
-        Arel::Nodes::BindParam.new "$#{index + 1}"
-      end
-
-      def exec_query(sql, name = 'SQL', binds = [])
-        log(sql, name, binds) do
-          result = binds.empty? ? exec_no_cache(sql, binds) :
-                                  exec_cache(sql, binds)
-
-          types = {}
-          result.fields.each_with_index do |fname, i|
-            ftype = result.ftype i
-            fmod  = result.fmod i
-            types[fname] = OID::TYPE_MAP.fetch(ftype, fmod) { |oid, mod|
-              warn "unknown OID: #{fname}(#{oid}) (#{sql})"
-              OID::Identity.new
-            }
-          end
-
-          ret = ActiveRecord::Result.new(result.fields, result.values, types)
-          result.clear
-          return ret
-        end
-      end
-
-      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
-      alias :exec_update :exec_delete
-
-      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
-
-        if pk && use_insert_returning?
-          sql = "#{sql} RETURNING #{quote_column_name(pk)}"
-        end
-
-        [sql, binds]
-      end
-
-      def exec_insert(sql, name, binds, pk = nil, sequence_name = nil)
-        val = exec_query(sql, name, binds)
-        if !use_insert_returning? && pk
-          unless sequence_name
-            table_ref = extract_table_ref_from_insert_sql(sql)
-            sequence_name = default_sequence_name(table_ref, pk)
-            return val unless sequence_name
-          end
-          last_insert_id_result(sequence_name)
-        else
-          val
-        end
-      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 ========================================
-
-      # Drops the database specified on the +name+ attribute
-      # and creates it again using the provided +options+.
-      def recreate_database(name, options = {}) #:nodoc:
-        drop_database(name)
-        create_database(name, options)
-      end
-
-      # Create a new PostgreSQL database. Options include <tt>:owner</tt>, <tt>:template</tt>,
-      # <tt>:encoding</tt>, <tt>:collation</tt>, <tt>:ctype</tt>,
-      # <tt>:tablespace</tt>, and <tt>:connection_limit</tt> (note that MySQL uses
-      # <tt>:charset</tt> while PostgreSQL uses <tt>:encoding</tt>).
-      #
-      # 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 :collation
-            " LC_COLLATE = '#{value}'"
-          when :ctype
-            " LC_CTYPE = '#{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
-
-      # 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)
-      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(/(^"|"$)/,'')}'
-            AND n.nspname = #{schema ? "'#{schema}'" : 'ANY (current_schemas(false))'}
-        SQL
-      end
-
-      # Returns true if schema exists.
-      def schema_exists?(name)
-        exec_query(<<-SQL, 'SCHEMA').rows.first[0].to_i > 0
-          SELECT COUNT(*)
-          FROM pg_namespace
-          WHERE nspname = '#{name}'
-        SQL
-      end
-
-      # Returns an array of indexes for the given table.
-      def indexes(table_name, name = nil)
-         result = query(<<-SQL, 'SCHEMA')
-           SELECT distinct i.relname, d.indisunique, d.indkey, pg_get_indexdef(d.indexrelid), t.oid
-           FROM pg_class t
-           INNER JOIN pg_index d ON t.oid = d.indrelid
-           INNER JOIN pg_class i ON d.indexrelid = i.oid
-           WHERE i.relkind = 'i'
-             AND d.indisprimary = 'f'
-             AND t.relname = '#{table_name}'
-             AND i.relnamespace IN (SELECT oid FROM pg_namespace WHERE nspname = ANY (current_schemas(false)) )
-          ORDER BY i.relname
-        SQL
-
-        result.map do |row|
-          index_name = row[0]
-          unique = row[1] == 't'
-          indkey = row[2].split(" ")
-          inddef = row[3]
-          oid = row[4]
-
-          columns = Hash[query(<<-SQL, "Columns for index #{row[0]} on #{table_name}")]
-          SELECT a.attnum, a.attname
-          FROM pg_attribute a
-          WHERE a.attrelid = #{oid}
-          AND a.attnum IN (#{indkey.join(",")})
-          SQL
-
-          column_names = columns.values_at(*indkey).compact
-
-          # add info on sort order for columns (only desc order is explicitly specified, asc is the default)
-          desc_order_columns = inddef.scan(/(\w+) DESC/).flatten
-          orders = desc_order_columns.any? ? Hash[desc_order_columns.map {|order_column| [order_column, :desc]}] : {}
-          where = inddef.scan(/WHERE (.+)$/).flatten[0]
-
-          column_names.empty? ? nil : IndexDefinition.new(table_name, index_name, unique, column_names, [], orders, where)
-        end.compact
-      end
-
-      # Returns the list of all column definitions for a table.
-      def columns(table_name)
-        # Limit, precision, and scale are all handled by the superclass.
-        column_definitions(table_name).map do |column_name, type, default, notnull, oid, fmod|
-          oid = OID::TYPE_MAP.fetch(oid.to_i, fmod.to_i) {
-            OID::Identity.new
-          }
-          PostgreSQLColumn.new(column_name, default, oid, type, notnull == 'f')
-        end
-      end
-
-      # Returns the current database name.
-      def current_database
-        query('select current_database()', 'SCHEMA')[0][0]
-      end
-
-      # Returns the current schema name.
-      def current_schema
-        query('SELECT current_schema', 'SCHEMA')[0][0]
-      end
-
-      # Returns the current database encoding format.
-      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
-
-      # Returns the current database collation.
-      def collation
-        query(<<-end_sql, 'SCHEMA')[0][0]
-          SELECT pg_database.datcollate FROM pg_database WHERE pg_database.datname LIKE '#{current_database}'
-        end_sql
-      end
-
-      # Returns the current database ctype.
-      def ctype
-        query(<<-end_sql, 'SCHEMA')[0][0]
-          SELECT pg_database.datctype FROM pg_database WHERE pg_database.datname LIKE '#{current_database}'
-        end_sql
-      end
-
-      # Returns an array of schema names.
-      def schema_names
-        query(<<-SQL, 'SCHEMA').flatten
-          SELECT nspname
-            FROM pg_namespace
-           WHERE nspname !~ '^pg_.*'
-             AND nspname NOT IN ('information_schema')
-           ORDER by nspname;
-        SQL
-      end
-
-      # Creates a schema for the given schema name.
-      def create_schema schema_name
-        execute "CREATE SCHEMA #{schema_name}"
-      end
-
-      # Drops the schema for the given schema name.
-      def drop_schema schema_name
-        execute "DROP SCHEMA #{schema_name} CASCADE"
-      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')
-          @schema_search_path = schema_csv
-        end
-      end
-
-      # Returns the active schema search path.
-      def schema_search_path
-        @schema_search_path ||= query('SHOW search_path', 'SCHEMA')[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:
-        result = serial_sequence(table_name, pk || 'id')
-        return nil unless result
-        result.split('.').last
-      rescue ActiveRecord::StatementInvalid
-        "#{table_name}_#{pk || 'id'}_seq"
-      end
-
-      def serial_sequence(table, column)
-        result = exec_query(<<-eosql, 'SCHEMA')
-          SELECT pg_get_serial_sequence('#{table}', '#{column}')
-        eosql
-        result.rows.first.first
-      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 @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, '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
-        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 = query(<<-end_sql, 'PK and serial sequence')[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?
-          # If that fails, try parsing the primary key's default value.
-          # Support the 7.x and 8.0 nextval('foo'::text) as well as
-          # the 8.1+ nextval('foo'::regclass).
-          result = query(<<-end_sql, 'PK and custom sequence')[0]
-            SELECT attr.attname,
-              CASE
-                WHEN split_part(def.adsrc, '''', 2) ~ '.' THEN
-                  substr(split_part(def.adsrc, '''', 2),
-                         strpos(split_part(def.adsrc, '''', 2), '.')+1)
-                ELSE split_part(def.adsrc, '''', 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 def.adsrc ~* 'nextval'
-          end_sql
-        end
-
-        [result.first, result.last]
-      rescue
-        nil
-      end
-
-      # Returns just a table's primary key
-      def primary_key(table)
-        row = exec_query(<<-end_sql, 'SCHEMA').rows.first
-          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 = '#{table}'::regclass
-        end_sql
-
-        row && row.first
-      end
-
-      # 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')
-      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
-
-      # 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 = {})
-        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
-
-      # Changes the column of a table.
-      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
-
-      # Changes the default value of a table column.
-      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
-
-      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
-
-      # Renames a column in a table.
-      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
-
-      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)
-        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
-        when 'datetime'
-          return super unless precision
-
-          case precision
-            when 0..6; "timestamp(#{precision})"
-            else raise(ActiveRecordError, "No timestamp type has precision of #{precision}. The allowed range of precision is from 0 to 6")
-          end
-        else
-          super
-        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 do |s|
-          s = s.to_sql unless s.is_a?(String)
-          s.gsub(/\s+(ASC|DESC)\s*(NULLS\s+(FIRST|LAST)\s*)?/i, '')
-        end
-        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
-
       module Utils
         extend self
 
@@ -1364,6 +513,7 @@ module ActiveRecord
       end
 
       protected
+
         # Returns the version of the connected PostgreSQL server.
         def postgresql_version
           @connection.server_version
@@ -1385,21 +535,22 @@ module ActiveRecord
         end
 
       private
-      def initialize_type_map
-        result = execute('SELECT oid, typname, typelem, typdelim FROM pg_type', 'SCHEMA')
-        leaves, nodes = result.partition { |row| row['typelem'] == '0' }
 
-        # populate the leaf nodes
-        leaves.find_all { |row| OID.registered_type? row['typname'] }.each do |row|
-          OID::TYPE_MAP[row['oid'].to_i] = OID::NAMES[row['typname']]
-        end
+        def initialize_type_map
+          result = execute('SELECT oid, typname, typelem, typdelim FROM pg_type', 'SCHEMA')
+          leaves, nodes = result.partition { |row| row['typelem'] == '0' }
 
-        # populate composite types
-        nodes.find_all { |row| OID::TYPE_MAP.key? row['typelem'].to_i }.each do |row|
-          vector = OID::Vector.new row['typdelim'], OID::TYPE_MAP[row['typelem'].to_i]
-          OID::TYPE_MAP[row['oid'].to_i] = vector
+          # populate the leaf nodes
+          leaves.find_all { |row| OID.registered_type? row['typname'] }.each do |row|
+            OID::TYPE_MAP[row['oid'].to_i] = OID::NAMES[row['typname']]
+          end
+
+          # populate composite types
+          nodes.find_all { |row| OID::TYPE_MAP.key? row['typelem'].to_i }.each do |row|
+            vector = OID::Vector.new row['typdelim'], OID::TYPE_MAP[row['typelem'].to_i]
+            OID::TYPE_MAP[row['oid'].to_i] = vector
+          end
         end
-      end
 
         FEATURE_NOT_SUPPORTED = "0A000" # :nodoc: