instance method indexes

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 634
      def indexes(table_name, name = nil)
         schemas = schema_search_path.split(/,/).map { |p| quote(p) }.join(',')
         result = query(<<-SQL, name)
           SELECT distinct i.relname, d.indisunique, d.indkey, t.oid
             FROM pg_class t, pg_class i, pg_index d
           WHERE i.relkind = 'i'
             AND d.indexrelid = i.oid
             AND d.indisprimary = 'f'
             AND t.oid = d.indrelid
             AND t.relname = '#{table_name}'
             AND i.relnamespace IN (SELECT oid FROM pg_namespace WHERE nspname IN (#{schemas}) )
          ORDER BY i.relname
        SQL


        indexes = []

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

          columns = query(<<-SQL, "Columns for index #{row[0]} on #{table_name}").inject({}) {|attlist, r| attlist[r[1]] = r[0]; attlist}
          SELECT a.attname, a.attnum
          FROM pg_attribute a
          WHERE a.attrelid = #{oid}
          AND a.attnum IN (#{indkey.join(",")})
          SQL

          column_names = indkey.map {|attnum| columns[attnum] }
          IndexDefinition.new(table_name, index_name, unique, column_names)

        end

        indexes
      end