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Fixed bug #21698: erroneously a field could be replaced by an

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equal constant under any circumstances.
In fact this substitution can be allowed if the field is
not of a type string or if the field reference serves as 
an argument of a comparison predicate.
This commit is contained in:
igor@rurik.mysql.com
2006-09-07 11:06:37 -07:00
parent ca3229dc1b
commit 34206c6f80
10 changed files with 247 additions and 24 deletions
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17
sql/sql_select.cc
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@ -6593,8 +6593,8 @@ static bool check_equality(Item *item, COND_EQUAL *cond_equal)
SYNOPSIS
build_equal_items_for_cond()
cond condition(expression) where to make replacement
inherited path to all inherited multiple equality items
cond condition(expression) where to make replacement
inherited path to all inherited multiple equality items
DESCRIPTION
At each 'and' level the function detects items for equality predicates
@ -6608,7 +6608,9 @@ static bool check_equality(Item *item, COND_EQUAL *cond_equal)
The function also traverses the cond tree and and for each field reference
sets a pointer to the multiple equality item containing the field, if there
is any. If this multiple equality equates fields to a constant the
function replace the field reference by the constant.
function replaces the field reference by the constant in the cases
when the field is not of a string type or when the field reference is
just an argument of a comparison predicate.
The function also determines the maximum number of members in
equality lists of each Item_cond_and object assigning it to
cond_equal->max_members of this object and updating accordingly
@ -6756,9 +6758,14 @@ static COND *build_equal_items_for_cond(COND *cond,
/*
For each field reference in cond, not from equal item predicates,
set a pointer to the multiple equality it belongs to (if there is any)
as soon the field is not of a string type or the field reference is
an argument of a comparison predicate.
*/
cond= cond->transform(&Item::equal_fields_propagator,
(byte *) inherited);
byte *dummy;
cond= cond->compile(&Item::subst_argument_checker,
&dummy,
&Item::equal_fields_propagator,
(byte *) inherited);
cond->update_used_tables();
}
return cond;