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  1. MariaDB ColumnStore
  2. MCOL-4065

DISTINCT is case sensitive

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      DISTINCT, as in SELECT DISTINCT c1 from t1 is currently a binary compare in Columnstore. It needs to be utf and case insensitive (for collations that are case insensitve).

      SELECT DISTINCT

      This script demonstrates the problem:

      DROP TABLE IF EXISTS t1;
      		 
      CREATE TABLE t1 (a VARCHAR(20) CHARACTER SET latin1) ENGINE=ColumnStore;
      		 
      INSERT INTO t1 VALUES ('a'),('b'),('A'),('B');
      		 
      SELECT DISTINCT a FROM t1;


      +------+
      		 
      | a    |
      		 
      +------+
      		 
      | a    |
      		 
      | b    |
      		 
      | A    |
      		 
      | B    |
      		 
      +------+

      Notice, all four rows returned.

      The expected result should consist of two rows only:

      +------+
      		 
      | a    |
      		 
      +------+
      		 
      | a    |
      		 
      | b    |
      		 
      +------+

      SELECT COUNT(DISTINCT)

      DROP TABLE IF EXISTS t1;
      		 
      CREATE TABLE t1 (a VARCHAR(20) CHARACTER SET latin1) ENGINE=ColumnStore;
      		 
      INSERT INTO t1 VALUES ('a'),('b'),('A'),('B');
      		 
      SELECT COUNT(DISTINCT a) FROM t1;


      +-------------------+
      		 
      | COUNT(DISTINCT a) |
      		 
      +-------------------+
      		 
      |                 4 |
      		 
      +-------------------+

      Looks wrong. The expected result is 2.

      SELECT..GROUP BY

      DROP TABLE IF EXISTS t1;
      		 
      CREATE TABLE t1 (a VARCHAR(20) CHARACTER SET latin1) ENGINE=ColumnStore;
      		 
      INSERT INTO t1 VALUES ('a'),('b'),('A'),('B');
      		 
      SELECT a FROM t1 GROUP BY a;


      +------+
      		 
      | a    |
      		 
      +------+
      		 
      | A    |
      		 
      | a    |
      		 
      | B    |
      		 
      | b    |
      		 
      +------+

      Looks wrong. The expected result should contain only two rows.

      Attachments

        Issue Links

          is blocked by

          Task - A task that needs to be done. MCOL-4422 Remove mariadb.h and my_sys.h dependency from collation.h

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

          Bug - A problem which impairs or prevents the functions of the product. MCOL-4388 Equality does not respect the NOPAD collation attribute

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MCOL-4417 Non-equality comparison operators do not work well with NOPAD collations

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MCOL-4498 LIKE is not collation aware

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

          Bug - A problem which impairs or prevents the functions of the product. MCOL-4575 Hash table performance for collation aware DISTINCT

          • Major - Major loss of function.
          • Open

          Task - A task that needs to be done. MCOL-495 Make string comparison not case sensitive

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

          Bug - A problem which impairs or prevents the functions of the product. MCOL-4064 Make JOIN collation aware

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

          Bug - A problem which impairs or prevents the functions of the product. MCOL-4539 WHERE short_char_column='literal' ignores the collation on a huge table

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MCOL-4721 CHAR(1) is not collation-aware for GROUP/DISTINCT

          • Major - Major loss of function.
          • Closed
          split from

          Bug - A problem which impairs or prevents the functions of the product. MCOL-3536 Order by with UTF

          • Major - Major loss of function.
          • Closed

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              dleeyh Daniel Lee (Inactive)
              David.Hall David Hall (Inactive)
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              Dates

                Created:
                Updated:
                Resolved:

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