Uploaded image for project: 'MariaDB Server'
  1. MariaDB Server
  2. MDEV-20541

Implement a flag to show if an expression is non-deterministic

    XMLWordPrintable

Details

    • Task
    • Status: Stalled (View Workflow)
    • Major
    • Resolution: Unresolved
    • None
    • Optimizer
    • None

    Description

      Deterministic expression is an expression that doesn't use non-deterministic functions.
      Non-deterministic function is a function that for equal input sets returns the same result set.

      E.g.: LENGTH() function of VARCHAR fields.
      'a' = 'a '
      But
      LENGTH('a') = 1 != 2 = LENGTH('a ')

      So, for equal input variables LENGTH() function returns different results.
      Therefore, LENGTH() of VARCHARs is non-deterministic.

      This task is a subtask for MDEV-11588.
      Non-deterministic expressions of GROUP BY fields are not functionally dependent on GROUP BY fields. Therefore, can't be used in SELECT list, HAVING and ORDER BY clauses.

      Attachments

        Issue Links

          Activity

            People

              serg Sergei Golubchik
              shagalla Galina Shalygina (Inactive)
              Votes:
              0 Vote for this issue
              Watchers:
              5 Start watching this issue

              Dates

                Created:
                Updated:

                Time Tracking

                  Estimated:
                  Original Estimate - Not Specified
                  Not Specified
                  Remaining:
                  Remaining Estimate - 0d
                  0d
                  Logged:
                  Time Spent - 3d 7h
                  3d 7h

                  Git Integration

                    Error rendering 'com.xiplink.jira.git.jira_git_plugin:git-issue-webpanel'. Please contact your Jira administrators.