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Merge bk-internal:/home/bk/mysql-4.1/

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into serg.mylan:/usr/home/serg/Abk/mysql-4.1
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serg@serg.mylan
2003-10-31 14:25:38 +01:00
parent 74551a72ec 35fe0d898d
commit b1f5a03685
16 changed files with 655 additions and 29 deletions
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59
sql/sql_select.cc
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@ -4172,6 +4172,60 @@ propagate_cond_constants(I_List<COND_CMP> *save_list,COND *and_father,
}
/*
Eliminate NOT functions from the condition tree.
SYNPOSIS
eliminate_not_funcs()
cond condition tree
DESCRIPTION
Eliminate NOT functions from the condition tree where it's possible.
Recursively traverse condition tree to find all NOT functions.
Call neg_transformer() method for negated arguments.
NOTE
If neg_transformer() returned a new condition we call fix_fields().
We don't delete any items as it's not needed. They will be deleted
later at once.
RETURN
New condition tree
*/
COND *eliminate_not_funcs(COND *cond)
{
if (!cond)
return cond;
if (cond->type() == Item::COND_ITEM) /* OR or AND */
{
List_iterator<Item> li(*((Item_cond*) cond)->argument_list());
Item *item;
while ((item= li++))
{
Item *new_item= eliminate_not_funcs(item);
if (item != new_item)
VOID(li.replace(new_item)); /* replace item with a new condition */
}
}
else if (cond->type() == Item::FUNC_ITEM && /* 'NOT' operation? */
((Item_func*) cond)->functype() == Item_func::NOT_FUNC)
{
COND *new_cond= ((Item_func*) cond)->arguments()[0]->neg_transformer();
if (new_cond)
{
/*
Here we can delete the NOT function. Something like: delete cond;
But we don't need to do it. All items will be deleted later at once.
*/
new_cond->fix_fields(current_thd, 0, &new_cond);
cond= new_cond;
}
}
return cond;
}
static COND *
optimize_cond(COND *conds,Item::cond_result *cond_value)
{
@ -4180,8 +4234,11 @@ optimize_cond(COND *conds,Item::cond_result *cond_value)
*cond_value= Item::COND_TRUE;
return conds;
}
/* change field = field to field = const for each found field = const */
DBUG_EXECUTE("where",print_where(conds,"original"););
/* eliminate NOT operators */
conds= eliminate_not_funcs(conds);
DBUG_EXECUTE("where", print_where(conds, "after negation elimination"););
/* change field = field to field = const for each found field = const */
propagate_cond_constants((I_List<COND_CMP> *) 0,conds,conds);
/*
Remove all instances of item == item