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  1. MariaDB Server
  2. MDEV-32732

Support DESC indexes in loose scan optimization

Details

    Description

      Group-min-max (aka Loose Scan) optimization does not work for reverse-ordered indexes:

      looking in opt_range.cc one can see in get_best_group_min_max() :

            for (uint i= 0; i < table->actual_n_key_parts(cur_index_info); i++)
      		 
            {
      		 
              if (cur_index_info->key_part[i].key_part_flag & HA_REVERSE_SORT)
      		 
              {
      		 
                cause="Reverse-ordered (not supported yet)";
      		 
                goto next_index;
      		 
              }
      		 
            }

      This task is to support it.

      Attachments

        Issue Links

          includes

          Bug - A problem which impairs or prevents the functions of the product. MDEV-36118 Wrong result in loose index scan

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-36220 ASAN unknown-crash in loose index scan of MIN with IS NULL

          • Major - Major loss of function.
          • Closed
          relates to

          Task - A task that needs to be done. MDEV-27576 Use DESC indexes for MIN/MAX optimization

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-36220 ASAN unknown-crash in loose index scan of MIN with IS NULL

          • Major - Major loss of function.
          • Closed

          Activity

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            View 8 older comments
            ycp Yuchen Pei added a comment -

            Hi psergei, ptal thanks:

            https://github.com/MariaDB/server/pull/3872

            ycp Yuchen Pei added a comment - Hi psergei , ptal thanks: https://github.com/MariaDB/server/pull/3872
            psergei Sergei Petrunia added a comment -

            Review input provided. One item left to address..

            psergei Sergei Petrunia added a comment - Review input provided. One item left to address..
            ycp Yuchen Pei added a comment -

            Thanks for the review psergei. I've updated my patch accordingly.

            Hi lstartseva, ptal thanks:

            0d710fb6dc9 bb-12.0-mdev-32732 MDEV-32732 Support DESC indexes in loose scan optimization

            ycp Yuchen Pei added a comment - Thanks for the review psergei . I've updated my patch accordingly. Hi lstartseva , ptal thanks: 0d710fb6dc9 bb-12.0-mdev-32732 MDEV-32732 Support DESC indexes in loose scan optimization
            lstartseva Lena Startseva added a comment -

            Testing done, Ok to push
            But before pushing, ycp, plz, change the description for testcase in desc_index_range.test

            --echo #
            		 
            --echo # Check that "Using index for group-by" is disabled (it's not supported, yet)
            		 
            --echo #

            lstartseva Lena Startseva added a comment - Testing done, Ok to push But before pushing, ycp , plz, change the description for testcase in desc_index_range.test --echo # --echo # Check that "Using index for group-by" is disabled (it's not supported, yet) --echo #
            ycp Yuchen Pei added a comment -

            Thanks for the testing. Push blocked by failure of main.timezone (see bb-12.0-mdev-32732 2769cce834bda986096423ac3d5899dbf1d81e27) which I believe requires a merge of 11.8->main which is blocked by some galera failures see https://mariadb.slack.com/archives/C03ER9QC3/p1744098547234689

            ycp Yuchen Pei added a comment - Thanks for the testing. Push blocked by failure of main.timezone (see bb-12.0-mdev-32732 2769cce834bda986096423ac3d5899dbf1d81e27) which I believe requires a merge of 11.8->main which is blocked by some galera failures see https://mariadb.slack.com/archives/C03ER9QC3/p1744098547234689

            People

              ycp Yuchen Pei
              psergei Sergei Petrunia
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              Dates

                Created:
                Updated:

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