Uploaded image for project: 'MariaDB Server'
  1. MariaDB Server
  2. MDEV-14589

InnoDB should not lock a delete-marked record

    XMLWordPrintable

    Details

      Description

      When a transaction is able to delete-mark a record and commit the change, no active transaction may possibly have seen (and locked) the record. The record can be removed by the purge thread at any time, and it is logically equivalent to a gap (non-existing record).

      However, currently InnoDB transactions will lock committed delete-marked records.

      How to repeat:
      Run at least 3 identical DELETE statements in parallel, and possibly some INSERT with a key value slightly smaller than that of the deleted record. InnoDB should report a bogus deadlock between 2 DELETE statements:

      trx (1) has obtained an X-lock on the delete-marked committed record
      trx (2) is waiting for an X-lock on the record and the preceding gap
      trx (1) is waiting for an X-lock on the record and the preceding gap

      Suggested fix:
      Transactions should ignore committed delete-marked records when they come across them.

      The solution we will try to implement is that when using isolation level is READ COMMITTED then DELETE will ignore any delete marked rows.

      This is same as https://bugs.mysql.com/bug.php?id=19762

        Attachments

          Issue Links

            Activity

              People

              Assignee:
              marko Marko Mäkelä
              Reporter:
              monty Michael Widenius
              Votes:
              1 Vote for this issue
              Watchers:
              6 Start watching this issue

                Dates

                Due:
                Created:
                Updated:
                Resolved: