[MDEV-16888] Add virtual Type_handler::cond_notnull_field_isnull_to_field_eq_zero() Created: 2018-08-03  Updated: 2018-08-03  Resolved: 2018-08-03

Status: Closed
Project: MariaDB Server
Component/s: Data types
Fix Version/s: 10.4.0

Type: Task Priority: Major
Reporter: Alexander Barkov Assignee: Alexander Barkov
Resolution: Fixed Votes: 0
Labels: None

Issue Links:
Blocks
blocks MDEV-4912 Data type plugin API version 1 Closed

 Description   

The code rewriting "datetime_field IS NULL" to "datetime_field='0000-00-00'" has tests for field_type():

class Item_func_isnull :public Item_func_null_predicate
 
{
 
  ..
 
  bool arg_is_datetime_notnull_field()
 
  {
 
    Item **args= arguments();
 
    if (args[0]->real_item()->type() == Item::FIELD_ITEM)
 
    {
 
      Field *field=((Item_field*) args[0]->real_item())->field;
 
 
 
      if (((field->type() == MYSQL_TYPE_DATE) ||
 
          (field->type() == MYSQL_TYPE_DATETIME)) &&
 
          (field->flags & NOT_NULL_FLAG))
 
        return true;
 
    }
 
  ..
 
};


COND *
 
Item_func_isnull::remove_eq_conds(THD *thd, Item::cond_result *cond_value,
 
                                  bool top_level_arg)
 
{
 
 ..
 
   if (((field->type() == MYSQL_TYPE_DATE) ||
 
        (field->type() == MYSQL_TYPE_DATETIME)) &&
 
        (field->flags & NOT_NULL_FLAG))
 
  ..
 
}

This is not friendly to new data types.

We'll remove these tests and add a new method in Type_handler_instead:

  virtual bool cond_notnull_field_isnull_to_field_eq_zero() const
 
  {
 
    return false;
 
  }

and override it for Type_handler_date_common and Type_handler_datetime_common to return true.
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