def prefetch_primary_key?(table_name = nil)
      return true if table_name.nil?
      do_not_prefetch_hash = @@do_not_prefetch_primary_key
      do_not_prefetch = do_not_prefetch_hash[ table_name = table_name.to_s ]
      if do_not_prefetch.nil?
        owner, desc_table_name, db_link = @connection.describe(table_name, default_owner)
        do_not_prefetch_hash[table_name] = do_not_prefetch =
          ! has_primary_key?(table_name, owner, desc_table_name, db_link) ||
          has_primary_key_trigger?(table_name, owner, desc_table_name, db_link)
      end
      ! do_not_prefetch
    end
def prefetch_primary_key?(table_name = nil)
      return true if table_name.nil?
      do_not_prefetch_hash = @@do_not_prefetch_primary_key
      do_not_prefetch = do_not_prefetch_hash[ table_name = table_name.to_s ]
      if do_not_prefetch.nil?
        owner, desc_table_name, db_link = @connection.describe(table_name, default_owner)
        do_not_prefetch_hash[table_name] = do_not_prefetch =
          ! has_primary_key?(table_name, owner, desc_table_name, db_link) ||
          has_primary_key_trigger?(table_name, owner, desc_table_name, db_link)
      end
      ! do_not_prefetch
    end
Returns true for Oracle adapter (since Oracle requires primary key
 values to be pre-fetched before insert).
 @see #next_sequence_value
 @override