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  1. MariaDB Server
  2. MDEV-27653

long uniques don't work with unicode collations

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      Description

      set names utf8;
      		 
      create table t1 (a text collate utf8_general_ci unique);
      		 
      show create table t1;
      		 
      insert t1 values ('a');
      		 
      insert t1 values ('ä');
      		 
      select * from t1;
      		 
      select distinct * from t1;
      		 
      select 'a' = 'ä';
      		 
      drop table t1;

      shows that one can insert two characters into a long unique index that compare equally.

      It happens because calc_hash_for_unique() hashes string length in bytes together with the string content. So even if two utf8 strings hash to the same value, they can have different length in bytes and long unique hash will be different.

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          Bug - A problem which impairs or prevents the functions of the product. MDEV-29954 Unique hash key on column prefix is computed incorrectly

          • Major - Major loss of function.
          • Stalled
          relates to

          Task - A task that needs to be done. MDEV-371 Unique indexes for blobs

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-28190 sql_mode makes MDEV-371 virtual column expressions nondeterministic

          • Critical - Crashes, loss of data, severe memory leak.
          • Stalled

          Bug - A problem which impairs or prevents the functions of the product. MDEV-29345 update case insensitive (large) unique key with insensitive change of value - duplicate key

          • Critical - Crashes, loss of data, severe memory leak.
          • Confirmed

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              Assignee:
              bar Alexander Barkov
              Reporter:
              serg Sergei Golubchik
              Votes:
              3 Vote for this issue
              Watchers:
              9 Start watching this issue

                Dates

                Created:
                Updated:
                Resolved:

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