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  1. MariaDB ColumnStore
  2. MCOL-4686

count(DINSTINCT) with a large number of distinct values runs forever

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    • Sprint:
      2021-8, 2021-9

      Description

      When attempting test200.sh, the test never finished.
      The query

      select count(distinct c1) as count2 from test200 where c1 <= 139000000;
      

      never returns. It takes around 3 minutes in 5.6.1.
      A little investigation shows an internal deadlock in fifo.h.

      Additionally, there appears to be a slowdown in lesser counts:

      select count(distinct c1) as count2 from test200 where c1 <= 13900000;
      

      takes almost 3 minutes in 6.1.1, but 15 seconds in 5.6.1.

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              Assignee:
              dleeyh Daniel Lee
              Reporter:
              David.Hall David Hall
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                Resolved:

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