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  1. MariaDB Server
  2. MDEV-13678

DELETE with CASCADE takes a long time when Galera is enabled

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      MDEV-13498 fixed a bug that DELETE with CASCADE was very slow due to a Galera-related check even when Galera was not enabled.

      After that fix, the operation is still slow when Galera is enabled.

      When I notified Seppo Jaakola about MDEV-13498, on August 17 he mentioned that the purpose of this condition is to avoid evaluating a potentially expensive condition. Now it seems that evaluating this filtering condition may cost more than the cost of evaluating the supposedly-expensive condition.
      I suggested the use of a lossy filter that would use a much simpler and faster data structure and algorithm than the std::find() on the std::deque, something like a hash table. This lossy filter would be allowed to fail safely, causing unnecessary evaluation of the supposedly-expensive condition.

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              Assignee:
              jplindst Jan Lindström
              Reporter:
              marko Marko Mäkelä
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