Index: vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
===================================================================
--- vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb	(revision 119)
+++ vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb	(working copy)
@@ -23,6 +23,10 @@
       def table_exists?(table_name)
         tables.include?(table_name.to_s)
       end
+      
+      def function_definition_for(function_name)
+        Function.new(function_name)
+      end
 
       # Returns an array of indexes for the given table.
       # def indexes(table_name, name = nil) end
Index: vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
===================================================================
--- vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb	(revision 119)
+++ vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb	(working copy)
@@ -470,6 +470,37 @@
         end
     end
 
+    # Defines what we need to know about an SQL function.
+    class Function
+      attr_reader :calling_sql, :arguments, :return_type, :result_cast_code, :returns_set
+      
+      def initialize(function_name, catalog_info)
+        @function_name, @catalog_info = function_name, catalog_info
+        @arguments = extract_arguments
+        @result_type, @result_cast_code = extract_result_type
+        @returns_set = extract_returns_set
+        @calling_sql = extract_calling_sql
+      end
+      
+      private
+      
+        def extract_calling_sql
+          raise NotImplementedError
+        end
+      
+        def extract_arguments
+          raise NotImplementedError
+        end
+        
+        def extract_result_type
+          raise NotImplementedError
+        end
+      
+        def extract_returns_set
+          raise NotImplementedError
+        end
+    end
+
     # Represents a SQL table in an abstract way for updating a table.
     # Also see TableDefinition and SchemaStatements#create_table
     #
Index: vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
===================================================================
--- vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb	(revision 119)
+++ vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb	(working copy)
@@ -70,6 +70,14 @@
       def quote_table_name(name)
         quote_column_name(name)
       end
+      
+      def quote_function_name(function_name)
+        quote_table_name(function_name)
+      end
+      
+      def quote_schema_name(schema_name)
+        quote_table_name(schema_name)
+      end
 
       # REFERENTIAL INTEGRITY ====================================
 
Index: vendor/rails/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
===================================================================
--- vendor/rails/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb	(revision 119)
+++ vendor/rails/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb	(working copy)
@@ -39,6 +39,42 @@
   end
 
   module ConnectionAdapters
+    class PostgreSQLFunction < Function
+      private
+        def extract_calling_sql
+          if returns_set
+            "SELECT * FROM #{@function_name}(%s)"
+          else
+            "SELECT #{@function_name}(%s)"
+          end
+        end
+      
+        def extract_arguments
+          i = -1
+          @catalog_info['arguments'].map do |arg|
+            i += 1
+            column = PostgreSQLColumn.new(nil, nil, arg)
+            {:class => column.klass, :cast_code => column.type_cast_code("args[#{i}]")}
+          end
+        end
+        
+        def extract_result_type
+          column = PostgreSQLColumn.new(nil, nil, @catalog_info['type'])
+          [column.klass, column.type_cast_code('value')]
+        end
+        
+        def extract_returns_set
+          case @catalog_info['returns_set']
+          when 'f'
+            false
+          when 't'
+            true
+          else
+            raise ArgumentError
+          end
+        end
+    end
+    
     # PostgreSQL-specific extensions to column definitions in a table.
     class PostgreSQLColumn < Column #:nodoc:
       # Instantiates a new PostgreSQL column definition in a table.
@@ -527,6 +563,44 @@
            WHERE schemaname IN (#{schemas})
         SQL
       end
+      
+      def self.relation_name_parts(relation_name)
+        parts = relation_name.split('.')
+        if parts.length == 1
+          relation = relation_name
+          schema = select_value('SHOW search_path').split(',').detect{|s| s =~ /^[a-z_\-]+$/i} rescue 'public'
+        elsif parts.length == 2
+          schema, relation = parts
+        else
+          raise ArgumentError
+        end
+        
+        [schema, relation]
+      end
+      
+      def function_definition_for(function_name)
+        schema, relation = self.class.relation_name_parts(function_name)
+        
+        catalog_info = select_one(%{
+          SELECT proc.proargtypes AS arguments, type.typname AS type, proc.proretset AS returns_set FROM pg_catalog.pg_proc AS proc
+            JOIN pg_catalog.pg_namespace AS namespace ON namespace.oid = proc.pronamespace
+            JOIN pg_catalog.pg_type AS type ON type.oid = proc.prorettype
+          WHERE proc.proname = '#{relation}' AND namespace.nspname = '#{schema}'
+        })
+        
+        unless catalog_info
+          raise Base::SQLFunctionNotFound, "SQL Function #{function_name} doesn't exist."
+        end
+        
+        catalog_info['arguments'] = catalog_info['arguments'].split.map do |argument|
+          select_value(%{
+            SELECT typname FROM pg_catalog.pg_type
+            WHERE oid = #{argument}
+          })
+        end
+        
+        PostgreSQLFunction.new(function_name, catalog_info)
+      end
 
       # Returns the list of all indexes for a table.
       def indexes(table_name, name = nil)
Index: vendor/rails/activerecord/lib/active_record/sql_methods.rb
===================================================================
--- vendor/rails/activerecord/lib/active_record/sql_methods.rb	(revision 0)
+++ vendor/rails/activerecord/lib/active_record/sql_methods.rb	(revision 0)
@@ -0,0 +1,80 @@
+module ActiveRecord
+  module SQLMethods
+    class SQLMethodError < ActiveRecordError #:nodoc:
+    end
+    
+    class SQLFunctionNotFound < SQLMethodError #:nodoc:
+    end
+    
+    def self.included(base) #:nodoc:
+      base.extend ClassMethods
+    end
+    
+    module ClassMethods
+      def build_argument_cast(var_name, argument) #:nodoc:
+        if argument[:cast_code] == nil
+          "#{var_name} = connection.quote(#{var_name})"
+        else
+          "#{var_name} = #{argument[:cast_code]}"
+        end
+      end
+      
+      def build_argument_casts(arguments) #:nodoc:
+        i = -1
+        arguments.collect do |argument|
+          i += 1
+          var_name = "args[#{i}]"
+          build_argument_cast(var_name, argument)
+        end
+      end
+      
+      def build_function_call(function) #:nodoc:
+        function.returns_set ? build_function_set_call(function) : build_function_scalar_call(function)
+      end
+      
+      def build_function_set_call(function) #:nodoc:
+        query = function.calling_sql
+        %{query = sprintf('#{query}', args.join(', '))
+          connection.select_values(query).map do |value|
+            #{function.result_cast_code}
+          end}
+      end
+      
+      def build_function_scalar_call(function) #:nodoc:
+        query = function.calling_sql
+        %{query = sprintf('#{query}', args.join(', ))
+          value = connection.select_value(query)
+          #{function.result_cast_code}}
+      end
+      
+      def sql_method(method_name)
+        function_name = "#{table_name}_#{method_name}"
+        function = connection.function_definition_for(function_name)
+        argument_casts = build_argument_casts(function.arguments)
+        call_code = build_function_call(function)
+
+        method_body = %{
+          def #{method_name}(*args)
+            unless args.length == #{function.arguments.length}
+              raise ArgumentError, sprintf('wrong number of arguments (%d for #{function.arguments.length})', args.length)
+            end
+            #{argument_casts.join("\n")}
+            #{call_code}
+          end}
+        
+        define_sql_method(method_name, method_body)
+      end
+      
+      def define_sql_method(method_name, method_code) #:nodoc:
+        begin
+          instance_eval(method_code, __FILE__, __LINE__)
+        rescue SyntaxError => err
+          if logger
+            logger.warn("An exception was raised during compilation of the sql method #{method_name}.")
+            logger.warn(err.message)
+          end
+        end
+      end
+    end
+  end
+end
\ No newline at end of file
Index: vendor/rails/activerecord/lib/active_record.rb
===================================================================
--- vendor/rails/activerecord/lib/active_record.rb	(revision 119)
+++ vendor/rails/activerecord/lib/active_record.rb	(working copy)
@@ -56,6 +56,7 @@
 require 'active_record/serialization'
 require 'active_record/attribute_methods'
 require 'active_record/dirty'
+require 'active_record/sql_methods'
 
 ActiveRecord::Base.class_eval do
   extend ActiveRecord::QueryCache
@@ -75,6 +76,7 @@
   include ActiveRecord::Reflection
   include ActiveRecord::Calculations
   include ActiveRecord::Serialization
+  include ActiveRecord::SQLMethods
 end
 
 require 'active_record/connection_adapters/abstract_adapter'