instance method indexes

# File activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 153
        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

            unless column_names.empty?
              # 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]
              using = inddef.scan(/USING (.+?) /).flatten[0].to_sym

              IndexDefinition.new(table_name, index_name, unique, column_names, [], orders, where, nil, using)
            end
          end.compact
        end