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Fixed bug #32815.

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The index (key_part_1, key_part-2) was erroneously considered as compatible
with the required ordering in the function test_test_if_order_by_key when 
a query with an ORDER BY clause contained a condition of the form
  key_part_1=const OR key_part_1 IS NULL 
and the order list contained only key_part_2. This happened because the value
of the const_key_parts field in the KEYUSE structure was not formed correctly
for the keys that could be used for ref_or_null access. 
This was fixed in the code of the update_ref_and_keys function.
The problem could not manifest itself for MyISAM databases because the
implementation of the keys_to_use_for_scanning() handler function always
returns an empty bitmap for the MyISAM engine.
This commit is contained in:
igor@olga.mysql.com
2007-12-07 17:14:59 -08:00
parent 55d6d04df0
commit c394dbe14a
3 changed files with 28 additions and 1 deletions
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2
sql/sql_select.cc
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@@ -3691,7 +3691,7 @@ update_ref_and_keys(THD *thd, DYNAMIC_ARRAY *keyuse,JOIN_TAB *join_tab,
found_eq_constant=0;
for (i=0 ; i < keyuse->elements-1 ; i++,use++)
{
if (!use->used_tables)
if (!use->used_tables && use->optimize != KEY_OPTIMIZE_REF_OR_NULL)
use->table->const_key_parts[use->key]|= use->keypart_map;
if (use->keypart != FT_KEYPART)
{