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  1. MariaDB Server
  2. MDEV-465

Optimizer : wrong index choice, leading to strong performances issues

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    Description

      Hi,

      I'm recreating in JIRA a Launchpad bug opened 2 years ago (https://bugs.launchpad.net/maria/+bug/639949), which is itself a follow up of a really annoying MySQL optimiser bug opened 4 years ago (http://bugs.mysql.com/bug.php?id=36817)

      To summarize, there are several simple cases where MySQL optimiser doesn't select the right index. This entails strong performance issues (especially when filesorting is involved), and force the developers to hack their applications, using USE INDEX (when it's possible...).

      Hoping someone finally takes a look at this serious issue...
      Actually it could also help some of my customers to switch to mariadb, because they are also a little bit tired to put USE INDEX everywhere in there code

      Thanks and regards,
      Jocelyn Fournier

      Attachments

        Issue Links

          duplicates

          Bug - A problem which impairs or prevents the functions of the product. MDEV-626 LP:639949 - Non optimal index choice, depending on index creation order

          • Closed
          relates to

          Bug - A problem which impairs or prevents the functions of the product. MDEV-6384 It seems like OPTIMIZER take into account the order of indexes in the table.

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

          Web Link Bug #36817 Non optimal index choice, depending on index creation order

          Activity

            Transition Time In Source Status Execution Times
            Sergei Petrunia made transition -
            Open In Progress
            		4d 13h 37m 1
            Sergei Petrunia made transition -
            In Progress Stalled
            		358d 23h 54m 1
            Sergei Petrunia made transition -
            Stalled Closed
            		388d 45m 1

            People

              psergei Sergei Petrunia
              joce jocelyn fournier
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              Dates

                Created:
                Updated:
                Resolved:

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