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Re: Please review: MDEV-7824 [Bug #68041] Zero date can be inserted in strict no-zero mode through a default value


Hi, Alexander!

On Mar 25, Alexander Barkov wrote:
> Hi Sergei,
> Please review a patch for mdev-7824.
> It's based on a MySQL patch for
> http://bugs.mysql.com/bug.php?id=68041
> and is a blocker for:
> MDEV-3929 Add full support for auto-initialized/updated timestamp and 
> datetime

That looks good.

But I don't like it that you verify defaults for every row.
It's not very cheap. And neither defaults nor sql_mode can change in the
duration of one statement. It should be enough to test only once.

I'm not sure, though, how to do that with a minimal overhead. A couple
of bool's in TABLE, like

   bool all_default_are_checked;
   bool write_set_defaults_are_checked;

that are set to false at the beginning on INSERT,INSERT...SELECT,LOAD.
And used like that

  bool TABLE::restore_record_and_validate_unset_fields(THD *thd, bool all)
    restore_record(this, s->default_values);
    if (all ? all_default_are_checked : write_set_defaults_are_checked)
      return false;

    if (all) all_default_are_checked= true;
    else write_set_defaults_are_checked= true;

    return validate_default_values_of_unset_fields(thd);

and in mysql_insert():

     if (fields.elements || !value_count)
       if (table->restore_record_and_validate_unset_fields(thd, !value_count))


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