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  1. MariaDB Server
  2. MDEV-28846

Poor performance when rowid filter contains no elements

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      See details in the attached test case. If we create the right spread of values in the key and pick the range just right, when rowid_filter optimizer switch is enabled, the optimizer will sacrifice a part of the key for the rowid_filter. As a result we use only the u_delete_user and end up examining 5K+ rows out of 10K in the table. If we disable rowid_filter, the user_name constraint is being used, and we examine only 1 row.

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        1. optimizer-trace-rowid-filter-off.txt
          7 kB
          Luis Eduardo Oliveira Lizardo
        2. optimizer-trace-rowid-filter-on.txt
          9 kB
          Luis Eduardo Oliveira Lizardo
        3. rowid_filter_bug.test
          750 kB
          Sasha Pachev

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              igor Igor Babaev
              spachev Sasha Pachev
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