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This commit is contained in:
Sergey Petrunia
2008-07-17 22:28:42 +04:00
parent 6cac08bcfb 7f16afccfb
commit 19e2ed7642
5 changed files with 70 additions and 62 deletions
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29
sql/sql_select.cc
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@ -12508,6 +12508,9 @@ part_of_refkey(TABLE *table,Field *field)
@note
used_key_parts is set to correct key parts used if return value != 0
(On other cases, used_key_part may be changed)
Note that the value may actually be greater than the number of index
key parts. This can happen for storage engines that have the primary
key parts as a suffix for every secondary key.
@retval
1 key is ok.
@ -12580,11 +12583,27 @@ static int test_if_order_by_key(ORDER *order, TABLE *table, uint idx,
reverse=flag; // Remember if reverse
key_part++;
}
*used_key_parts= on_primary_key ? table->key_info[idx].key_parts :
(uint) (key_part - table->key_info[idx].key_part);
if (reverse == -1 && !(table->file->index_flags(idx, *used_key_parts-1, 1) &
HA_READ_PREV))
reverse= 0; // Index can't be used
if (on_primary_key)
{
uint used_key_parts_secondary= table->key_info[idx].key_parts;
uint used_key_parts_pk=
(uint) (key_part - table->key_info[table->s->primary_key].key_part);
*used_key_parts= used_key_parts_pk + used_key_parts_secondary;
if (reverse == -1 &&
(!(table->file->index_flags(idx, used_key_parts_secondary - 1, 1) &
HA_READ_PREV) ||
!(table->file->index_flags(table->s->primary_key,
used_key_parts_pk - 1, 1) & HA_READ_PREV)))
reverse= 0; // Index can't be used
}
else
{
*used_key_parts= (uint) (key_part - table->key_info[idx].key_part);
if (reverse == -1 &&
!(table->file->index_flags(idx, *used_key_parts-1, 1) & HA_READ_PREV))
reverse= 0; // Index can't be used
}
DBUG_RETURN(reverse);
}