igor@olga.mysql.com c394dbe14a Fixed bug #32815. ...

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.

2007-12-07 17:14:59 -08:00

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