Commit ed80a84f authored by unknown's avatar unknown
Browse files

Fix for bug#5782: Don't choose the plan that accesses table with index_prev if... 

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)
parent fb1b8476

sql/sql_select.cc

+6 −12
Original line number Diff line number Diff line
@@ -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)

	  {