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  1. MariaDB Server
  2. MDEV-26939

support descending indexes for simple ORDER BY

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    Description

      in cases like

      CREATE TABLE t1 (a INT, b INT, INDEX (a DESC, b ASC));
      ...
      SELECT * FROM t1 ORDER BY a DESC, b ASC;
      

      In other cases descending indexes could be treated as disabled.

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            ORDER BY seems to be working already:

            sql/sql_select.cc

            23449
                const ORDER::enum_order keypart_order= 
            23450
                  (key_part->key_part_flag & HA_REVERSE_SORT) ? 
            23451
                  ORDER::ORDER_DESC : ORDER::ORDER_ASC;
            23452
                /* set flag to 1 if we can use read-next on key, else to -1 */
            23453
                flag= (order->direction == keypart_order) ? 1 : -1;
            

            serg Sergei Golubchik added a comment - ORDER BY seems to be working already: sql/sql_select.cc 23449 const ORDER::enum_order keypart_order= 23450 (key_part->key_part_flag & HA_REVERSE_SORT) ? 23451 ORDER::ORDER_DESC : ORDER::ORDER_ASC; 23452 /* set flag to 1 if we can use read-next on key, else to -1 */ 23453 flag= (order->direction == keypart_order) ? 1 : -1;

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              serg Sergei Golubchik
              serg Sergei Golubchik
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              Dates

                Created:
                Updated:
                Resolved:

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