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Fix for bug#5782: Don't choose the plan that accesses table with index_prev if the handler doesn't support it (see also ChangeSet@1.2039)

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tomas@poseidon.ndb.mysql.com 2004-10-01 15:47:56 +00:00
parent 5e8ce3841a
commit 22c07a6be9
1 changed files with 6 additions and 12 deletions
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18
sql/sql_select.cc
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@ -6923,7 +6923,10 @@ static int test_if_order_by_key(ORDER *order, TABLE *table, uint idx,
reverse=flag; // Remember if reverse
key_part++;
}
*used_key_parts= (uint) (key_part - table->key_info[idx].key_part);
uint tmp= (uint) (key_part - table->key_info[idx].key_part);
if (reverse == -1 && !(table->file->index_flags(idx,tmp-1, 1) & HA_READ_PREV))
DBUG_RETURN(0);
*used_key_parts= tmp;
DBUG_RETURN(reverse);
}
@ -7120,10 +7123,6 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
*/
if (!select->quick->reverse_sorted())
{
// here used_key_parts >0
if (!(table->file->index_flags(ref_key,used_key_parts-1, 1)
& HA_READ_PREV))
DBUG_RETURN(0); // Use filesort
// ORDER BY range_key DESC
QUICK_SELECT_DESC *tmp=new QUICK_SELECT_DESC(select->quick,
used_key_parts);
@ -7144,9 +7143,6 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
Use a traversal function that starts by reading the last row
with key part (A) and then traverse the index backwards.
*/
if (!(table->file->index_flags(ref_key,used_key_parts-1, 1)
& HA_READ_PREV))
DBUG_RETURN(0); // Use filesort
tab->read_first_record= join_read_last_key;
tab->read_record.read_record= join_read_prev_same;
/* fall through */
@ -7188,13 +7184,11 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
for (nr=0; nr < table->keys ; nr++)
{
uint used_key_parts;
uint not_used;
if (keys.is_set(nr))
{
int flag;
if ((flag=test_if_order_by_key(order, table, nr, &used_key_parts)) > 0 ||
((flag < 0) && (table->file->index_flags(nr,used_key_parts-1, 1)
& HA_READ_PREV)))
if (flag=test_if_order_by_key(order, table, nr, &not_used))
{
if (!no_changes)
{