Uploaded image for project: 'MariaDB Server'
  1. MariaDB Server
  2. MDEV-6480

Remove conditions for which range optimizer returned SEL_ARG::IMPOSSIBLE.

        Details

          Description

          This task is a "cut the Gordian Knot" approach to solving the problem described in two comments here:

          https://mariadb.atlassian.net/browse/MDEV-6454?focusedCommentId=55355&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-55355

          https://mariadb.atlassian.net/browse/MDEV-6454?focusedCommentId=55358&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-55358

          The idea is that as soon as range optimizer concludes that some for Item* (possibly inside an OR) we have produced a tree of type SEL_ARG::IMPOSSIBLE, that Item* should be removed from the WHERE condition.

          The will solve the problem described in the above two comments, and also will open additional optimization possibilities.

          Challenges to explore

          • How does one remove Item* from the WHERE in a PS-safe way (call thd->change_item_tree() or ... ?)
          • Do we need to do AND/OR flattening after such conversion?

            Gliffy Diagrams

              Attachments

                Issue Links

                relates to

                Bug - A problem which impairs or prevents the functions of the product. MDEV-6454 Performance degradation (suboptimal execution plan) on a query with expected range access

                • Major - Major loss of function.
                • Closed

                  Activity

                  Ascending order - Click to sort in descending order
                  Hide
                  Permalink
                  psergey Sergei Petrunia added a comment -

                  The fix is pushed to https://github.com/MariaDB/server/tree/bb-10.1-orderby-fixes

                  Show
                  psergey Sergei Petrunia added a comment - The fix is pushed to https://github.com/MariaDB/server/tree/bb-10.1-orderby-fixes
                  Hide
                  Permalink
                  psergey Sergei Petrunia added a comment -

                  Pushed into 10.1 tree

                  Show
                  psergey Sergei Petrunia added a comment - Pushed into 10.1 tree

                    People

                    • Assignee:
                      psergey Sergei Petrunia
                      Reporter:
                      psergey Sergei Petrunia
                    • Votes:
                      0 Vote for this issue
                      Watchers:
                      2 Start watching this issue

                      Dates

                      • Created:
                        Updated:
                        Resolved: