# File lib/dm-migrations/sql/postgresql.rb, line 50
      def query_column_constraints
        @adapter.query(
          "SELECT * FROM information_schema.table_constraints WHERE table_name='#{@name}' AND table_schema=current_schema()"
        ).each do |table_constraint|
          @adapter.query(
            "SELECT * FROM information_schema.constraint_column_usage WHERE constraint_name='#{table_constraint.constraint_name}' AND table_schema=current_schema()"
          ).each do |constrained_column|
            @columns.each do |column|
              if column.name == constrained_column.column_name
                case table_constraint.constraint_type
                when "UNIQUE"       then column.unique = true
                when "PRIMARY KEY"  then column.primary_key = true
                end
              end
            end
          end
        end
      end