A comment for view_prepare_mode.

  bool drop_if_exists, drop_temporary, local_file, one_shot_set;

  bool in_comment, ignore_space, verbose, no_write_to_binlog;

  bool tx_chain, tx_release;

  /* special JOIN::prepare mode: changing of query is prohibited */

  /*

    Special JOIN::prepare mode: changing of query is prohibited.

    When creating a view, we need to just check its syntax omitting

    any optimizations: afterwards definition of the view will be

    reconstructed by means of ::print() methods and written to

    to an .frm file. We need this definition to stay untouched.

  */

  bool view_prepare_mode;

  bool safe_to_cache_query;

  bool subqueries, ignore;